Method of coating film, coating unit, aging unit, solvent replacement unit, and apparatus for coating film

ABSTRACT

Prior to transfer of an wafer W, a mixed gas is being generated and exhausted, thereby fluctuation of concentration and temperature of a solvent component at the beginning of gas introduction into a chamber  3  is suppressed. A step of gelling after the wafer W is carried into an aging unit is divided into several steps. Until a temperature of the wafer W reaches a predetermined treatment temperature, an average concentration of the solvent component in a mixed gas is gradually raised relative to the temperature of the wafer W. Thereby, immediately after the wafer W is transferred into a sealed chamber, the gas of the solvent component is prevented from condensing.

This application is a division of patent application Ser. No. 09/210,759filed Dec. 14, 1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a coating method of forming aninsulating film by coating a coating liquid dispersed therein particlesor colloids destined to be a starting material of a film component in asolvent on a surface of a substrate, and relates to a coating unit, anaging unit, and a solvent replacement unit, and a film coating apparatusfor coating a film.

2. Description of the Related Art

As a method of forming an interlayer insulating film of a semiconductordevice, CVD and thermal oxidation are well known. On the other hand,other than these, there is a method called a sol-gel method. In thissol-gel method, a coating liquid dispersed colloids of TEOS(tetra-ethoxysilane; (Si(C₂H₅O)₄) in an organic solvent such as ethanolsolution is coated on a surface of a semiconductor wafer (hereinafter,simply refers to as wafer), the coated film, after being gelled, isdried, to obtain a silicon oxide film. The examples of this sol-gelmethod are disclosed in Japanese Patent Laid-Open Application Nos.HEI-8-162450 and HEI-8-59362.

Behavior in the course of change of the coated film in this sol-gelmethod is shown schematically in FIG. 10A through FIG. 10C. First,particles or colloids 100 of the TEOS, when coated on a wafer, are in adispersed state in a solvent 200 (FIG. 10A). Then, this coated film, bybeing subjected to an basic atmosphere or to heating, is promoted inpolycondensation and hydrolysis of the TEOS. As the result, the coatedfilm is gelled to form a reticular structure of the TEOS 300 (FIG. 10B).

Next, in order to remove moisture in the coating liquid, the solvent inthe coated film is replaced by another solvent 400 of which boilingpoint is low and surface tension is small (FIG. 10C). By drying furtherthereafter, a coated film of a silicon oxide film is obtained.

Incidentally, a step of replacing the solvent shown in FIG. 10C iscarried out to remove moisture. Further, the step of replacing with thesolvent is carried out with an object to make the film hydrophobic. Thatis, since OH group is liable to absorb the moisture, the OH groupcombined to a terminal portion of Si—O bond is replaced by anotherorganic substance by cleaning the film with, for instance, HMDS or thelike.

Further, another object is to suppress collapse of a structure of thefilm by employing a solvent of smaller surface tension than ethanol sothat a large force is not placed on the reticular structure of the TEOSwhen the solvent vaporizes.

Thus, there are an uncountable number of minute pores in the siliconoxide film formed by the sol-gel method, there comes in air. Therefore,relative dielectric constant of the oxide film ε is close to that ofair. Therefore, the electric resistance of the oxide film including suchminute pores becomes such high as is close to that of air, resulting inan ideal insulating film.

In order to apply such a sol-gel method in an actual manufacturing line,a coating unit of coating a coating liquid on a wafer, an aging unit ofgelling the coated film by heating the wafer at a pre-determinedtemperature, for instance, at 100° C., and a replacement unit ofreplacing the solvent in the coated film by another solvent arenecessary. Further, a pre-treatment unit for carrying out thepretreatment such as hydrophobic treatment to the wafer, and a bakingunit of drying the wafer are also necessary. And, by disposing atransfer mechanism of transferring the wafers between respective units,an apparatus is constituted.

Now, upon carrying out gelling treatment of the coated film, it isnecessary that, through suppression of evaporation of the solvent fromthe coated film, gelling of the TEOS is made not to be disturbed. Forthis, it is not desirable to carry out gelling operation in an opensystem like the conventional method. Instead, the gelling treatmentneeds only to be carried out in a sealed container of an atmospherefilled with vapor of the solvent. That is, after disposing a wafer on astage heated at a pre-determined temperature in the sealed container,gas including vapor of the solvent needs only to be introduced.

Now, the inventors of the present invention investigated to carry outthe gelling operation with an aging unit 3 of a structure illustrated inFIG. 11, for instance. The aging unit 3 comprises a heating plate 30, acover 33 provided with a heater, a gas introducing path 34, and a gasexhausting path 35.

As shown in FIG. 11, in this aging unit 3, the heating plate 30 isformed of ceramic and incorporates a heater 31 a.

The cover 33 is provided with a heater. This cover 33 is intimatelyconnected to a circumference portion of the heating plate 30 through asealing member 32, and, together with the heating plate 30, constitutesa sealed container defining a treatment chamber S.

In the heating plate 30, outside along the circumference portion of thewafer W, a gas introducing inlet 34 a is formed in slit. This gasintroducing inlet 34 a penetrates the heating plate 30 and is connectedto a gas introducing path 34 introducing gas from the outsides.

At the central portion of the cover 33, an exhausting outlet 35 a isdisposed. This exhausting outlet 35 a penetrates the cover 33 to connectthe exhausting path 35 communicating with the outsides. In addition, tothe aging unit 3, 3 pieces of pins 36 for going up and down aredisposed, for instance, and with these pins for going up and down, thewafer W is moved up and down between the heating plate 30 and the aboveposition thereof.

As a gas to be employed here, a gas of a solvent component, forinstance, vapor of ethylene glycol, is employed in order to suppressevaporation of the solvent inside the coated film during the atmospherefor heat treatment is heated.

And the gas introducing path 34 is disposed penetrating the heatingplate 30. Therefore, the gas is introduced into the sealed containerafter being heated to approximately 100° C., for instance, or atemperature extremely close to that temperature. At this time, theconcentration of the vapor of ethylene glycol is a concentration that isequal with the saturated vapor pressure at a treatment temperature ofapproximately 100° C., for instance. Further, in addition to ethyleneglycol, a gas accelerating gelation, ammonia gas, for instance, can beintroduced simultaneously.

However, in such a sealed container as the aging unit 3 shown in FIG.11, when introduction of gas therein is started, there is such a problemthat until supply of the gas reaches a steady state, the concentrationand temperature of the gas fluctuate.

Also as aforementioned, in the case of a wafer being processed at apre-determined temperature higher than normal temperature, 100° C., forinstance, when the wafer of the room temperature is transferred as it isinto the sealed container of a pre-determined temperature, the gas ofthe solvent component which is at the saturated vapor pressure in thesealed container contacts with the wafer, to lower the temperaturethereof. As the result, it becomes a supersaturated state, and the gasof the solvent component is likely to condense. When ethylene glycol,for instance, condenses on the wafer, the thickness of that part becomesthick, resulting in a problem of becoming a non-homogeneous insulatingfilm.

SUMMARY OF THE INVENTION

The first invention of the present application is made to solve such aproblem.

That is, an object of the first invention is to provide a method ofcoating a film which are capable of suppressing fluctuation oftemperature and concentration at the starting time of gas introductioninto a sealed container, capable of preventing the solvent componentfrom condensation immediate after transfer of a substrate, for instance,an wafer into the sealed container, and capable of obtaining thereby athin film, for instance, an interlayer insulating film, of an excellentquality, an aging unit, and an apparatus of coating a film.

For this, a method of coating a film of the first invention comprises:

a step of forming a film by coating a liquid, in which particles orcolloids of a starting material of a film component is dispersed in asolvent, on a surface of a substrate;

a first gelling step of, in addition to transferring of the substrateinto a sealed container, gelling the substrate in a state of the coatedsubstrate being exposed to gas including vapor of the solvent of thecoating liquid at a first average concentration; and

a second gelling step of gelling in a state where the insides of thesealed container is filled by a gas including the vapor of the solventof the coating liquid at a second average concentration higher than thefirst average concentration.

Further, an aging unit for carrying out this method of forming the filmcomprises:

a treatment chamber accommodating a substrate thereon a film including asolvent and particles or colloids of starting material of a filmcomponent is formed;

a heater of heating the substrate;

a carrier gas feeding system feeding the carrier gas towards thetreatment chamber;

a solvent dispensing system of dispensing the solvent towards thetreatment chamber;

a mixing system forming a gas mixture containing vapor of the solventfrom the carrier gas feeding system and the solvent dispensing system;and

an adjusting mechanism for adjusting concentration of the solvent in thegas mixture.

Further, an apparatus of forming a film for carrying out theaforementioned method of forming the film comprises:

a coating unit of coating a liquid in which particles or colloids of astarting material of a film component is dispersed on a surface of asubstrate;

an aging unit comprising a treatment chamber accommodating a substratethereon a film is formed, a heater heating the substrate, a carrier gasfeeding system feeding a carrier gas towards the treatment chamber, asolvent dispensing system dispensing the solvent towards the treatmentchamber, a mixing system forming a gas mixture containing vapor ofsolvent from the carrier gas feeding system and the solvent dispensingsystem, an adjustment mechanism adjusting concentration of the solventof the gas mixture, and

a solvent replacement unit replacing the solvent in the coated film.

In the aforementioned method, the gas introduced into the sealedcontainer in the first gelling step is preferable to be adjusted intemperature to approximately a temperature of the inside of the sealedcontainer.

According to the first invention, after a substrate is transferred intoa sealed container until the temperature of the substrate reaches thepre-determined temperature, the average concentration of the solventcomponent is made low. On the other hand, when the temperature of thesubstrate becomes high, the concentration of the solvent component ismade high. Therefore, immediate after the substrate is transferred intothe sealed container, the gas of the solvent component can be preventedfrom condensation.

Incidentally, before transferring the substrate into the sealedcontainer, it is preferable that while a mixture of vapor of the solventcomponent and a carrier gas is formed, the gas mixture is beingexhausted. By implementing like this, the fluctuation of theconcentration of the solvent component and the temperature can besuppressed at the starting of gas introduction.

Specific examples of the first invention are cited as follows. A step ofgelling particles or colloids of the coated film is one that heats thesubstrate. Further, the gas to be introduced into the sealed containeris made by mixing a carrier gas and the vapor of the solvent component.The first gelling step is carried out by adjusting the flow rate of atleast one of the carrier gas or the vapor of the solvent component.Further, mixing of the carrier gas and the vapor of the solventcomponent is carried out at an evaporator which evaporates liquid of thesolvent component. The first gelling step is carried out by adjustingthe flow rate of the liquid of the solvent component being introducedinto the evaporator.

In this case, the first gelling step includes the step of varyingcontinuously the concentration of the vapor of the solvent component.Further, the first gelling step includes the step of mixingintermittently the vapor of the solvent component with the carrier gas.

Further, the second gelling step includes the step of, after the firstgelling step is carried out subsequent transfer of the substrate intothe sealed container, feeding the gas into the sealed container in astate where the average concentration of the vapor of the solventcomponent is higher than that during the first gelling step.

Further, an average concentration of the solvent of the gas beingexposed to the substrate at each step is preferable to be theconcentration corresponding to the saturated vapor pressure at thesubstrate temperature at each step. For instance, the aforementionedfirst average concentration is preferable to be the concentrationcorresponding to the saturated vapor pressure at the substratetemperature at the time of introduction of the container, the secondaverage concentration being preferable to be the concentrationcorresponding to the saturated vapor pressure at the substratetemperature during gelling.

The reason is that there is a problem that, when the averageconcentration of the solvent in the gas is lower than the saturatedvapor pressure, the solvent volatilizes from the coated film on thesubstrate, resulting in difficulty of generating pores in the film.

On the other hand, when the average concentration of the solvent in thegas is higher than the saturated vapor pressure, there is a problem thatthe vapor condenses on the substrate or on the wall of the treatmentchamber, the condensation on the substrate induces deterioration of thefilm quality, and the condensation on the wall of the treatment chambertends to cause contamination of the apparatus or re-sticking on thesubstrate.

Next, as the second invention, the inventors investigated to form aninterlayer insulating film by use of sol-gel method illustrated in FIG.10A to FIG. 10C.

Here, the inventors further attempted to replace the solvent in thecoated film by another solvent 400 (FIG. 10C). In this replacement stepof the solvent, after replacement of water in the coated film byethanol, for instance, HMDS (hexamethyl disilane) is supplied to removeOH group, and finally replacement by heptane is carried out.

The reason for employing heptane here is to suppress collapse of thefilm structure by avoiding, with use of a solvent of low surfacetension, a large power placed on a reticular structure of TEOS duringvaporization of the solvent.

When applying such a sol-gel method into an actual manufacturing line, acoating unit for coating a coating liquid on a wafer, a gelling unit forgelling the coated film and a replacement unit for replacing the solventin the coated film by another solvent are necessary.

In the replacement step of the solvent, because of use of 3 solvents asaforementioned, the present inventors attempted to employ a conventionalresist coating device for the replacement unit.

The resist coating device will be described with reference to FIG. 18.

The device comprises a vacuum chuck 194 which is capable of going up anddown and rotates a wafer while holding in a horizontal position, a fixedcup 195, and a nozzle 196 for dispensing a solvent to the wafer. Thefixed cup 195 is disposed such that it surrounds the wafer W on thechuck 194, and an opening portion at an upper surface is opened orclosed by the cup 195 a.

As the nozzle 196, 3 pieces of nozzles 196 a to 196 c which dischargeethanol, HMDS and heptane, respectively, are disposed. These nozzles of196 a to 196 c are taken out in this order by grasping by a carrying arm197 from nozzle receiving portions 198 a to 198 c, and are transferredup to around the central portion above the wafer W.

In the case of carrying out the solvent replacement step of the sol-gelmethod with such an apparatus, first, in a state where the cover 195 ais open, the wafer W is transferred to the chuck 194. Then, ethanol isdripped from the nozzle 196 a onto the wafer W, thereafter the fixed cup195 is closed, the wafer W is rotated. Thus, the ethanol is diffusedover the whole front surface of the wafer W through centrifugal force.Thereafter, the cover 195 a is opened, similarly HMDS is supplied on thesurface of the wafer W with the nozzle 196 b. Then, heptane is furthersupplied on the surface of the wafer W through the nozzle 196 c, tocarry out treatment.

However, in the aforementioned apparatus, since 3 pieces of nozzles 196prepared for the respective solvents are grasped by a carrying arm 197to transfer, when the solvent is supplied on the surface of the wafer W,after transfer by the nozzle 196 a, the nozzle 196 b is necessary to betransferred. That is, the carrying arm 197 was required to repeat to goand return several times between the nozzle receiving portion 198 and aposition above the wafer W. Further, each time one solvent is diffusedon the wafer W, the cover 195 a of the fixed cup 195 was necessary to beopened and closed.

Thus, the next solvent is impossible to be supplied continuouslysucceeding the supply of one solvent, supply of the solvent is stoppedto cause idle time.

Moreover, since until next supply of the solvent, a travelling time ofthe carrying arm 197 and an opening/closing time of the cover 195 a arepiled up, a certain degree of time is necessary.

When it takes time between replacements of the solvents and there is anidle time of the supply of the solvent, the solvent on the surface ofthe wafer, for instance, contacts with the air. Therefore, there occurssuch an inconvenience as that moisture in the air is confined in thefilm. And, as the result, the formed interlayer insulating film isdeteriorated in its film quality.

The second invention of the present application was made to solve such aproblem.

That is, an object of the second invention of the present application isto provide, in a method of forming a film having a step of carrying outreplacement of solvents by dispensing successively at least a pluralityof solvents on a surface of a substrate thereon a coated film is to beformed, a method of forming a film, a solvent replacement unit, and anapparatus for forming a film in which a preceding solvent and asucceeding solvent can be supplied continuously, thereby enabling toobtain an excellent thin film such as an interlayer insulating film.

Therefore, a method of forming a film of the second invention comprises:

a step of forming a film on a surface of a substrate by coating acoating liquid in which particles or colloids of a starting material ofa film component are dispersed in a solvent;

a step of gelling the particles or the colloids in the coated film; and

a step of dispensing at least 2 kinds of replacement solvents differentfrom the aforementioned solvent on the surface of the substrate byswitching successively;

wherein the switching of the replacement solvent to be supplied iscarried out by starting dispensing of the succeeding solvent whiledispensing the preceding replacement solvent, and thereafter by stoppingsupply of the preceding replacement solvent.

Further, a solvent replacement unit for carrying out this method ofcoating a film comprises:

a treatment vessel accommodating a substrate formed thereon a filmcontaining the solvent and particles or colloids of the startingmaterial of the film component;

a spin chuck holding the substrate disposed in the treatment vessel;

a plurality of solvent supply systems dispensing solvents towards thesubstrate; and

a switching device for switching the plurality of solvent dispensingsystems.

Further, an apparatus of forming a film for carrying out theaforementioned method of forming a film comprises:

a coating unit forming a film on a surface of a substrate by coating aliquid in which particles or colloids of the starting material of thefilm component are dispersed in a solvent;

an aging unit for gelling the coated film; and

a solvent replacement unit consisting of a treatment vesselaccommodating a substrate formed thereon a film containing the solventand particles or colloids of the starting material of the filmcomponent, a spin chuck holding the substrate disposed in the treatmentvessel, a plurality of solvent supply systems dispensing solvents to thesubstrate, and a switching device switching the plurality of solventsupply systems.

In the method of the second invention, since the supply of thesucceeding solvent begins before the supply of the preceding solvent isceased, the preceding solvent and the succeeding solvent arecontinuously supplied on the surface of the coated film without beinginterrupted. Thus, in the solvent replacement step, there is no time ofinterruption of supply of the solvent on the surface of the substratethereon the coated film is formed. Therefore, occurrence of such aninconvenience as that occurs due to stoppage of the supply of thesolvent, inclusion of moisture in the coated film, for instance, can besuppressed, resulting in formation of an excellent thin film on thesubstrate.

In the second invention, in the solvent replacement step, among theplurality kinds of solvents, at least 2 kinds of solvents may besupplied on a substrate from a common solvent dispensing portion, eachof the plurality of kinds of solvents may be supplied on the substratefrom separate solvent dispensing portions. Further, in the solventreplacement step, alcohol, a liquid for hydrophobic treatment, and asolvent of smaller surface tension than the solvent contained in thecoating liquid, for instance, are supplied in this order on thesubstrate.

Next, as the third invention, the inventors attempted to use spincoating, which is used in coating of resist, as a coating method. Inthis unit, on the central portion of the wafer sucked to a spin chuck,the coating liquid is dripped, the spin chuck is rotated to thin out thecoated film over the whole surface through centrifugal force to coat.

Now, since, during coating of a coating liquid, the wafer is rotatedwith high speed, air flow is generated along the surface of the wafer,resulting in speedy evaporation of the solvent in the coating liquid.Therefore, evaporation of the solvent is being tried to be suppressed byadjusting the temperature and humidity of the coating unit and thetemperature of the coating liquid. However, it is difficult to suppresssufficiently the evaporation of the solvent through only adjustment oftheir temperature and humidity. In addition, when the solvent evaporatesmuch, gelling of the solvent is disturbed to deteriorate the filmquality of the silicon oxide film.

The third invention of the present application was made to solve such aproblem.

That is, an object of the third invention is to provide a method offorming a film, a coating unit, and an apparatus of forming a filmwhich, when obtaining a film by coating a coating liquid dispersedtherein starting material of film components of colloids or particles ina solvent on the substrate, enable to obtain a thin film of excellentquality such as an interlayer insulating film.

For this, the third method of forming a film comprises:

a step of forming a film by coating a coating liquid, in which particlesor colloids of the starting material of a film component are dispersedin a solvent, on a surface of a substrate under an atmosphere filled bythe vapor of the solvent; and

a step of gelling the particles or colloids in the coated film;

wherein the vapor of the solvent contains one vapor of any one ofsolvent components.

As an example of a method of the third invention, a method of forming afilm comprising the following steps can be cited:

a step of transferring a substrate into a treatment vessel from aninlet;

a step of closing the inlet of the treatment vessel;

a step of filling the treatment vessel with vapor of a solvent;

a step of coating a coating liquid in which particles or colloids of thestarting material of the film component are dispersed in the solvent onthe surface of the substrate in the treatment vessel filled by thevapor; and

a step of gelling the particles or the colloids in the coated film.

As another example of the method of the third invention, a method offorming a film comprising the following steps can be cited:

a step of disposing a substrate on a rotary stage by transferring intothe treatment vessel from the inlet;

a step of closing the substrate inlet of the treatment vessel;

a step of filling the vapor by feeding vapor of the solvent into thetreatment vessel;

a step of, together with rotating a rotary stage, spreading a coatingliquid on the surface of the substrate by dispensing the coating liquid,in which particles or colloids of the starting material of the filmcomponent are dispersed in the solvent, on a surface of the substrate;and

a step of gelling the particles or the colloids in the coated film.

Further, a coating unit for carrying out this coating method comprises:

a treatment vessel accommodating a substrate;

a spin chuck holding the substrate disposed in the treatment vessel;

a coating liquid nozzle dispensing a coating liquid on the substrate;

a coating liquid supply system dispensing a coating liquid, in whichparticles or colloids of starting material of film component aredispersed in the solvent, to the coating liquid nozzle;

a solvent nozzle dispensing the solvent into the treatment vessel; and

a solvent supply system dispensing the solvent to the solvent nozzle.

Further, an apparatus of forming a film for carrying out theaforementioned film forming method comprises:

a coating unit forming the film on the substrate comprising a treatmentvessel accommodating a substrate, a spin chuck holding the substratedisposed in the treatment vessel, a coating liquid nozzle dispensing thecoating liquid to the substrate, a coating liquid supply systemdispensing a coating liquid, in which particles or colloids of thestarting material of film component are dispersed in the solvent, to thecoating liquid nozzle, a solvent nozzle dispensing the solvent into thetreatment vessel, and a solvent dispensing system dispensing the solventto the solvent nozzle;

an aging unit for gelling the coated film; and

a solvent replacement unit replacing the solvent in the coated film.

The third invention, after a film is formed on a surface of a substrate,while keeping an atmosphere therein the substrate is placed anatmosphere filled with vapor of the solvent, on the circumferenceportion of the substrate, a cleaning liquid of removing the coated filmmay be supplied to remove the coated film of the circumference portion.

In this case, the solvent contains a plurality kinds of organicsolvents. The third invention includes the case where the vapor is atleast one vapor of the plurality kinds of organic solvents.

For instance, the solvent contains ethylene glycol and alcohol, thevapor of the solvent is ethylene glycol. The starting material of thefilm component is a metal alkoxide, for instance.

Next, as the fourth invention, the inventors attempted to apply theaforementioned sol-gel method in an actual manufacturing line. That is,the inventors attempted to form a film by, in the step of forming afilm, dispensing a coating liquid, in which particles or colloids ofTEOS are dispersed in the solvent, on an approximately center ofrotation of the wafer surface, then by rotating the wafer around avertical axis, thereby spreading a coating liquid over the whole surfaceof the wafer by making use of centrifugal force of rotation.

Now, after the coating liquid is coated on the wafer, vaporization ofthe solvent is required to be suppressed not to disturb gelling of TEOS.For this, as one solvent components of the coating liquid, a solvent,which has a high boiling point and is difficult to evaporate, such asethylene glycol, is employed.

However, because of high viscosity of ethylene glycol, use of it as thesolvent causes the viscosity of the coating liquid itself.

On the other hand, on the surface of the wafer thereon an interlayerinsulating film is formed, due to disposition of aluminum wiring, thereis fine unevenness. Therefore, only by rotating the wafer after supplyof the coating liquid on the surface of the wafer as described above,the coating liquid is difficult to spread due to its viscosity.Accordingly, the coating liquid is difficult to come into the fineunevenness of the surface of the wafer, thus, there occurs a problemthat a film is difficult to be coated on the whole surface of the wafer.In recent years, in particular, finer pattern is a trend. As the trendof the fine pattern advances and the width of aluminum wiring becomesnarrow, the coating liquid is the more difficult to come into.

The fourth invention of the present application was carried out to solvesuch a problem.

That is, an object of the fourth invention is to provide a method offorming a film, a coating unit, and an apparatus of forming a film inwhich the coating liquid is easily coated on the surface of thesubstrate, thereby a film is formed universally all over the surface ofthe substrate, as a result, an excellent thin film such as an interlayerinsulating film can be obtained.

For this, a method of forming a film of the fourth invention comprises:

a step of coating the solvent of lower viscosity than the most viscouscomponent among the solvent components of the coating liquids in whichparticles or colloids of the starting material of the film component aredispersed in a solvent, and of capable of dissolving the startingmaterial, on the surface of the substrate;

a step of forming a film by coating the coating liquid on the surface ofthe substrate; and

a step of gelling particles or colloids in the coated film.

Here, as a starting material, tetraethoxysilane can be employed.Further, after the step of gelling, on the surface of the substratethereon a film is formed, the other solvent than the aforementioned oneis supplied, thereby the solvent replacement step for replacing thesolvent in the coated film by the different solvent may be carried out.

Further, a coating unit for carrying out this film forming methodcomprises:

a treatment vessel accommodating a substrate;

a spin chuck holding the substrate disposed in the treatment vessel;

a solvent nozzle dispensing solvent to the substrate;

a solvent supply system dispensing the solvent to the solvent nozzle;

a coating liquid nozzle dispensing the coating liquid to the substratethereto the solvent is supplied; and

a coating liquid supply system dispensing the coating liquid in whichparticles or colloids of the starting materials of film components aredispersed in the solvent to the coating liquid nozzle.

Further, an apparatus of forming a film for carrying out theaforementioned method for forming a film comprises:

a coating unit comprising a treatment vessel accommodating a substrate,a spin chuck holding the substrate disposed in the treatment vessel, asolvent nozzle dispensing solvent to the substrate, a solvent supplysystem dispensing solvent to the solvent nozzle, a coating liquid nozzledispensing coating liquid to substrate thereto the solvent is supplied,and a coating liquid supply system dispensing the coating liquid inwhich particles or colloids of the starting materials of film componentsis dispersed in the solvent to the coating liquid nozzle;

an aging unit for gelling the coated film; and

a solvent replacement unit for replacing the solvent in the coated film.

In the method according to the fourth invention, in the step of forminga film, before coating a coating liquid on a substrate, a solvent ofsmaller viscosity than that of the component of the most highestviscosity among the components of solvent of the coating liquid iscoated over the whole surface of the substrate. Accordingly, when thecoating liquid is supplied on the surface thereof, first, the startingmaterial of the coating liquid and water are dissolved in the solutioncoated over the whole surface of the substrate.

Thereby, due to mixing of the coating liquid and the solution, theviscosity of the coating liquid becomes low. Accordingly, the coatingliquid becomes easy to spread on the substrate, to be coated over thewhole surface of the substrate universally. As the result, a thin filmof excellent quality can be formed.

According to the method of the fourth invention, as a solution to becoated on a surface of a substrate before coating the coating liquid onthe surface of the substrate, one component of lower viscosity than thehighest one among the aforementioned components of the solvent may beemployed. In this case, since one solvent component is coated, when thecoating liquid is applied, this component and the coating liquid arelikely to be easily mixed. And, upon mixing thereof, there is nooccurrence of bubbles, accordingly a coated film of more excellentquality can be formed. Further, as a solution to be coated on thesurface of the substrate preceding the step of applying the coatingliquid on the surface of the substrate, alcohol can be employed. Sincealcohol can dissolve the aforementioned starting materials and water,effect as identical as the aforementioned method of the first disclosureof the fourth invention can be obtained.

Next, as the fifth invention, the inventors have studied a method offorming an interlayer insulating film by use of the aforementionedsol-gel method.

In the case of applying the aforementioned sol-gel method in an actualmanufacturing line, in the step of forming a film, the coating liquid issupplied approximately the center of rotation on the surface of thewafer, then the wafer is rotated. Thus, by spreading the coating liquidover the whole surface of the wafer by use of the centrifugal force ofrotation, a film is formed. In this case, the coating liquid is made bymixing TEOS and the solvent in advance, the mixed liquid (coatingliquid) is stored in a tank or the like, and the stored coating liquidis supplied on the surface of the wafer.

However, in the case of a film being formed with the coating liquidformed in advance and stored in a tank, there are some cases whereunevenness of the film thickness or film quality is confirmed byeye-inspection. According to observation by the inventors, in the caseof the coating liquid which has stood for a certain degree of timeperiod after mixing of TEOS and the solvent being coated on the wafer,deterioration of the film quality was experientially confirmed to occur.This is a problem.

The fifth invention of the present application was made to solve such aproblem.

That is, an object of the fifth invention is to provide a method offorming a film which can suppress deterioration of the film quality ofthe coated film, as a result, can obtain a thin film such as aninterlayer insulating film of excellent quality.

For this, a method of forming a film of the fifth invention comprises:

a step of mixing a first liquid containing particles or colloids of astarting material of a film component which is insoluble or difficult tobe dissolved in water and water, and a second liquid consisting of anorganic solvent which can dissolve water and the film component;

a step of coating, after completion of the aforementioned mixing, beforelapse of time in which the quality of the film obtained by the mixingdeteriorates, the mixed liquid containing the first liquid and thesecond liquid on the surface of the substrate; and

a step of gelling the particles or the colloids in the film coated onthe substrate.

According to the method of the fifth invention, after mixing of thefirst liquid and the second liquid, before lapse of the time periodwhere the film quality of the obtained coated film deteriorates, within6 min. after mixing for instance, the coating liquid is coated on thesurface of the substrate. Thereby, the film quality of the coated filmcan be suppressed from deterioration, resulting in an excellent thinfilm such as a silicon oxide film.

In this fifth invention, after a step of coating the mixed liquid whichdoes not stand the deterioration time of the film quality aftercompletion of mixing of the first and the second liquids, before coatingof the mixed liquid on the surface of the next substrate, a step ofcleaning the mixing portion of the first and second liquids and theinsides of the liquid path at the down-stream of the mixing portion withan organic solvent such as alcohol may be carried out.

In this case, the mixed liquid which remained in the liquid path andlapsed the film quality deteriorating time after mixing is cleared awayby the organic solvent. Therefore, upon treatment of the next substrate,the old mixed liquid remaining in the liquid path is not coated,accordingly deterioration of the film quality can be suppressed.

Further, when alcohol is employed as the organic solvent, since alcoholdissolves the starting materials of the film components and water,cleaning of the insides of the liquid path can be carried out readily.

Next, as the sixth invention, the inventors have studied another methodof forming a film with use of the aforementioned sol-gel method.

That is, in the aforementioned sol-gel method, after coating of thecoating liquid on the wafer, by standing for one night, for instance,the coated film is gelled. However, for mass production, gelation shouldbe carried out as fast as possible. As one method for this, heating ofthe wafer may be one candidate, however, in this case, the solvent inthe coated film is activated in evaporation.

For this, the inventors have studied, as the sixth invention, ofcarrying out gelation at, for instance, room temperature with use ofammonium gas (NH₃) containing water vapor.

The reason of containing moisture in ammonium gas is as follows. Thatis, a part of ammonium gas containing water vapor, upon sticking on thecoated film, is ionized such as

NH₃+H₂O→NH₄ ⁺+OH⁻.

That is, under presence of water, hydroxide group is formed to be basic.An alkali is a catalyst accelerating polycondensation and contributes togelation. From this, water vapor is necessary to be contained. And, asthe state approaches the saturated state due to much water vapor, OHgroups can be expected to be generated much, accordingly the rate ofgelation is considered to be fast.

In FIG. 35, a device being used when gelation is carried out withammonium gas containing water vapor close to the saturated state isillustrated.

The device 501 comprises a disposing stage 511 of an wafer W, atreatment vessel 510 capable of tight sealing consisting of a sealingmember 512 and a cover 513, a tank 521 storing commercial ammonia water(NH₄OH) (concentration of ammonia: 30% by weight at normal temperature)520, a bubbling gas supply pipe 522 of carrying out bubbling byintroducing ammonia gas into ammonia water 520 in the tank 521, anexhausting outlet 523 of exhausting the treatment gas generated bybubbling, and a piping 525 communicating the exhausting outlet 523 andthe gas introducing inlet 514 disposed at the disposing stage 511.

At normal temperature, ammonia water contains approximately 33% byweight of ammonia as saturated concentration. Therefore, if the bubblingis started at normal temperature with the commercial ammonia water as itis, first, ammonia gas is absorbed in the ammonia water. During this,ammonia gas is not generated or is not generated enough to obtaindesired flow rate if generated, accordingly gelation takes a long time.And, when the concentration of ammonia in the ammonia water attainsapproximately 33% by weight, the ammonia gas containing water vapor ofapproximately saturated concentration is generated as a treatment gas.The generated treatment gas is introduced into the treatment vessel 510through the piping 525 and is exhausted out through an exhausting path515 opened at a cover 513 of the treatment vessel 510.

However, in this device, as mentioned above, the commercial ammoniawater is employed as it is. Therefore, when continuous treatment of thewafer is implemented, if ammonia water 520 in the tank 521 isreplenished, the concentration of the ammonia water 520 is temporarilylowered and ammonia gas is absorbed. Accordingly, ammonia gas is notgenerated or, if generated, the desired flow rate can not be obtained.Therefore, there is a problem that gelation can not be completed,accordingly, the desired film thickness and film quality can not beobtained.

As a method preventing this from occurring, such a method is consideredthat, immediately before replenishment of ammonia water, gellingtreatment is interrupted, and, after the treatment gas begins to begenerated again, gelling is started again. However, upon carrying outlike this, there occurs a problem that serviceability ratio of thedevice goes down, thereby through-put also goes down.

The sixth invention of the present application is made to solve such aproblem.

That is, an object of the sixth invention is, upon gelling the coatedfilm with an ammonia gas, to provide a gas treatment method capable ofcarrying out stable treatment, and capable of treating evenly betweensubjects to be treated.

Another object of the sixth invention is to provide a method capable ofcarrying out stable treatment, without restricting in the case ofcarrying out gelling treatment with an ammonia gas, also in the case ofcarrying out treatment to the subjects to be treated with the treatmentgas.

For this, the method of forming a film of the sixth invention comprises:

a step of forming a film by coating a coating liquid, in which particlesor colloids of a starting material of a film component is dispersed in asolvent, on a surface of a substrate; and

a step of gelling the particles or colloids in the coated film byexposing the substrate to the ammonia gas;

wherein in the step of gelling, an ammonia gas is generated bysuccessively introducing the ammonia gas into at least 2 vesselsaccommodating ammonia water of ammonia concentration lower than thesaturated concentration, the ammonia gas generated precedently issupplied to the substrate, thereafter the succeedingly generated ammoniagas is supplied to the substrate, thereby conductance of the ammonia gassupplied to the substrate is maintained constant.

Further, an aging unit for carrying out the method of forming a filmcomprises:

a treatment vessel accommodating a substrate;

a plurality of ammonia containers accommodating ammonia water;

bubbling gas supply systems feeding a carrier gas for bubbling in therespective ammonia containers;

bubbling gas valves closing or opening the respective bubbling gassupply systems;

exhausting systems for exhausting gas generated in the respectiveammonia containers;

exhausting system valves for closing or opening the respectiveexhausting systems;

ammonia gas supply systems for feeding gas generated at the respectiveammonia containers to the treatment vessels;

ammonia gas valves closing or opening the respective ammonia gas supplysystems; and

a means for opening the respective bubbling gas valves in turn, at thesame time, synchronizing with this closing or opening of the respectivebubbling gas valves, closing respective exhausting system valves inturn, and opening the respective ammonia gas valves in turn.

Further, an apparatus of forming a film for carrying out theaforementioned method of forming a film comprises:

a coating unit for coating a coating liquid on a substrate;

an aging unit comprising a treatment vessel accommodating a substrate, aplurality of ammonia containers accommodating ammonia water, bubblinggas supply systems feeding a carrier gas for bubbling to the respectiveammonia containers, bubbling gas valves closing or opening therespective bubbling gas supply systems, exhausting systems forexhausting gas generated from the respective ammonia containers,exhausting system valves for closing or opening the respectiveexhausting systems, ammonia gas supply systems feeding the gas generatedat the respective ammonia containers to the treatment vessel, ammoniagas valves closing or opening the respective ammonia gas supply systems,and a means which opens in turn the respective bubbling gas valves, atthe same time, synchronizing with closing or opening of the respectivebubbling gas valves, closes in turn the respective exhausting systemvalves, and opens in turn the respective ammonia gas valves; and

a solvent replacement unit for replacing the solvent in the coated film.

Here, since the concentration of ammonia in ammonia water is lower thanthe saturated concentration, when ammonia water is replenished, ammoniagas, upon bubbling by it, is absorbed by ammonia water for a while.Therefore, it takes some time for ammonia gas containing vapor ofmoisture to be generated with stability.

According to the sixth invention, when ammonia water is replenished inthe precedent container, the first container, for instance, ammonia gasis being generated from the succeeding container, the second container,for instance, accordingly supply of the ammonia gas containing vapor ofmoisture is not interrupted, thereby stable treatment can be carriedout.

Further, by equalizing conductance of the path when gas flows from theprecedent container through the treatment vessel, conductance of thepath when gas flows from the precedent container through the firstexhausting path, conductance of the path when gas flows from thesucceeding container through the treatment vessel, and conductance ofthe path when gas flows from the succeeding container through the secondexhausting path, upon switching the path, fluctuation of flow rate andpressure of ammonia gas can be suppressed. Therefore, more stabletreatment can be carried out.

Further, a method of forming a film of the sixth invention comprises:

a step of forming a film by coating a coating liquid, in which particlesor colloids of a starting material of a film component is dispersed in asolvent, on a surface of a substrate; and

a step of gelling the particles or the colloids in the coated film byexposing the substrate to ammonia gas;

wherein the gelling step comprises:

a preliminary exhausting step of exhausting treatment gas from gassource without going through the treatment vessel but through theexhausting path;

a step of transferring the subject to be treated into the treatmentvessel; and

a treatment step of treating a subject to be treated by feeding thetreatment gas from the gas source into the treatment vessel by switchingthe path from the exhausting path to treatment vessel side;

wherein the conductance of the path upon flowing through the treatmentvessel from the gas source and conductance of path upon flowing throughexhausting path are made equal.

According to the sixth invention, fluctuation of the flow rate andpressure of the gas can be suppressed when the path of the gas isswitched, accordingly stable treatment can be carried out.

Next, the seventh invention will be described.

When the sol-gel method as described above is being applied in an actualmanufacturing line, a coating unit for coating a coating liquid on anwafer, a gelling unit for gelling the coated film, and a replacementunit for replacing the solvent in the coated film by another solvent arenecessary.

In addition, a pre-treatment unit for carrying out pretreatment such ashydrophobic treatment to the wafer, and a bake unit for drying the waferare also necessary. The device is constituted by further disposing atransferring mechanism for transferring the wafer between respectiveunits.

Now, when the coating liquid is coated on the wafer, the solvent, beingorganic solvent, evaporates. If the amount of evaporation is much, thereis a problem that the aimed film thickness and film quality can not beobtained.

The seventh invention of the present application is made to solve such aproblem.

That is, an object of the seventh invention is to provide an apparatusfor forming a film capable of carrying out the following step as soon aspossible after coating a coating liquid in which particles or colloidsof a starting material of a film components are dispersed in a solventon a substrate and capable of obtaining an excellent thin film such asinterlayer insulating film, for instance.

Therefore, the apparatus of forming a film of the seventh inventioncomprises: a coating portion of forming a film by coating a coatingliquid, in which particles or colloids of a starting material of a filmcomponents is dispersed in a solvent, on a substrate; a gellingtreatment portion which is disposed in neighborhood of this coatedportion and gels the particles or the colloids in the coated film formedon the coated portion; a plurality of pre-treatment portions forpre-treating prior to coating of the coating liquid on the substrate; aplurality of heating portions for drying the substrate after treatmentat the gelling treatment portion; a receiving portion receiving thesubstrate from the outside; a main transfer portion which, in additionto transferring to the coating portion through the pre-treatment portionafter reception of the substrate from the receiving portion, transfersthe substrate after treatment at the gelling treatment portion to theheating portion; and an auxiliary transfer portion transferring thesubstrate coated at the coating portion to the gelling treatmentportion.

According to the seventh invention, the substrate is transferred by anexclusive auxiliary transferring portion from the coating portion to thegelling treatment portion. Therefore, the substrate, immediately afterthe coating liquid is applied, is transferred to the next step, therebyevaporation of the solvent can be suppressed, resulting in a thin filmof excellent film quality.

Here, in the aforementioned apparatus for forming a film, on thetransferring path of the substrate in the auxiliary transferringportion, a means for feeding vapor of solvent component, for instance,ethylene glycol, can be provided with. Further, a case for covering thecoating portion and gelling treatment portion, and a means for feedingvapor of the solvent component into the case may be provided with. Inthis case, evaporation of the solvent in the coated film duringtransferring of the substrate can be further suppressed.

In the aforementioned apparatus for forming a film, a solventreplacement treatment portion which is disposed neighboring the gellingportion, supplies another solvent different from the aforementionedsolvent to the substrate treated at the gelling treatment portion, andreplaces the solvent in the coated film by another solvent, can beprovided, and the substrate treated at the gelling treatment portion maybe transferred to the solvent replacement treatment portion by anauxiliary transferring portion. In this case, since the time periodduring which large surface tension of the solvent is added on thereticular structure of TEOS is made short, collapse of the filmstructure is suppressed, resulting in a thin film of excellent quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing diagrammatically total configuration ofone example of an apparatus of forming a film being employed inpracticing the first invention.

FIG. 2A, FIG. 2B, FIG. 2C and FIG. 2D are diagrams for explaining flowof treatment of formation of a film in which the aforementionedapparatus of forming a film is employed.

FIG. 3 is a diagram diagrammatically showing one example of an agingunit and a gas feeding means in the aforementioned apparatus of forminga film.

FIG. 4 is a flow chart showing one example of flow of gelling treatmentaccording to the method of the first invention.

FIG. 5 is a characteristic diagram showing change on standing of wafertemperature and concentration of solvent vapor during the gellingtreatment according to the method of the first invention.

FIG. 6 is a diagram showing diagrammatically another example of the gasfeeding means.

FIG. 7 is a diagram showing diagrammatically another example of the gasfeeding means.

FIG. 8 is a characteristic diagram showing change on standing of wafertemperature and concentration of solvent vapor during the gellingtreatment in the case of the gas feeding means shown in FIG. 7 beingemployed.

FIG. 9 is a diagram showing diagrammatically another example of the gasfeeding means.

FIG. 10A, FIG. 10B and FIG. 10C are diagrams for explaining situation ofvariation of a coated film in sol-gel method.

FIG. 11 is a diagram showing diagrammatically one example of an agingunit being studied by the inventors.

FIG. 12 is a side view of a profile showing one example of a solventreplacement unit where a step of solvent replacement of the secondinvention is practiced.

FIG. 13 is a plan view showing a nozzle for solvent supply beingemployed in the aforementioned solvent replacement unit.

FIG. 14 is a diagram showing sequence of timings of closing and openingof valves for explaining a method of the second invention.

FIG. 15 is a side view of a profile showing another example of a solventreplacement unit where a step of solvent replacement of the secondinvention is practiced.

FIG. 16 is a plan view showing a solvent dispensing portion beingemployed in the solvent replacement unit.

FIG. 17 is a side view of a profile showing still another example of asolvent replacement unit where a step of solvent replacement of thesecond invention is practiced.

FIG. 18 is a cross-sectional view showing a conventional resist coatingdevice.

FIG. 19 is a side view of a profile showing an apparatus of forming afilm being employed when practicing a method of the third invention.

FIG. 20 is a plan view of a cross-section cut along A—A of the coatingunit of FIG. 19.

FIG. 21A, FIG. 21B and FIG. 21C are process diagrams showingsequentially a part of one example of processes of a method of the thirdinvention.

FIG. 22A, FIG. 22B and FIG. 22C are process diagrams showing processesfollowing the processes shown in FIG. 21A to FIG. 22C.

FIG. 23 is an exploded diagram showing a situation where the coated filmof the circumference portion of an wafer is removed by edge-rinsetreatment.

FIG. 24A and FIG. 24B are process diagrams showing processes aftercoating treatment.

FIG. 25 is a side view of a profile showing one example in which athree-way valve is attached to a solvent vapor feeding pipe of thecoating unit in the apparatus of forming a film.

FIG. 26 is a side view of a profile showing one example of a coatingunit where the process of forming a film of the method of the fourthinvention is practiced.

FIG. 27A, FIG. 27B, FIG. 27C and FIG. 27D are process diagrams forexplaining the solvent replacement process of the method of the fourthinvention.

FIG. 28A and FIG. 28B are process diagrams for explaining a gellingprocess and a solvent replacement process of the fourth invention.

FIG. 29 is a side view of a profile showing one example of a coatingunit where the treatment forming a film of the method of the fifthinvention is carried out.

FIG. 30A, FIG. 30B, FIG. 30C and FIG. 30D are process diagrams forexplaining the treatment of forming a film.

FIG. 31 is a characteristic diagram showing relation between coatingliquids and film quality of the coated film.

FIG. 32 is a diagram showing diagrammatically one example of an agingunit in the apparatus of forming a film employed upon practicing of themethod of the sixth invention.

FIG. 33 is a diagram showing diagrammatically one example of path of gasflow in the aging unit shown in FIG. 32.

FIG. 34 is a diagram showing diagrammatically another example of path ofgas flow in an aging unit.

FIG. 35 is a diagram showing diagrammatically a conventional aging unit.

FIG. 36 is a plan view showing one example of one embodiment of anapparatus of forming a film of the seventh invention.

FIG. 37 is a cross-sectional view showing one example of a coating/agingunit of the apparatus of forming a film.

FIG. 38 is a cross-sectional view showing one example of the coatingunit of the coating/aging unit.

FIG. 39 is a cross-sectional view showing one example of the aging unitof the coating/aging unit.

FIG. 40 is a cross-sectional view showing one example of a solventreplacement unit of the apparatus of forming a film.

FIG. 41 is a plan view showing another example of a coating/aging unit.

FIG. 42 is a perspective view showing another example of a coating/agingunit.

FIG. 43 is a plan view showing another example of an apparatus offorming a film.

FIG. 44 is a plan view showing still another example of an apparatus offorming a film.

FIG. 45 is a plan view showing still another example of an apparatus offorming a film.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, the details of specific examples of the presentinvention will be described with reference to drawings. Incidentally,the scope of the present invention should not be construed to berestricted to the range of the following examples.

EXAMPLE 1

FIG. 1 is a plan view showing diagrammatically an apparatus of forming afilm which is employed upon practicing the method of example 1 involvingthe first invention of the present application. Reference numeral 11denotes an input/output port of wafers W which are substrates. At thisinput/output port 11, from a cassette C disposed on a cassette stage CS,a carrying arm 12, after pulling out an wafer W, supplies to a main arm13.

On one side of guide rails 14 which is transferring path of a main arm13, a coating unit 2 which is a coating portion constituting a mainportion of the apparatus, together with an aging unit 3 which is agelling treatment portion and a solvent replacement unit 4 which is asolvent replacing portion, is arranged in this order. Also on the otherside of the transferring path 14, treatment units U1 to U4 are arranged.To these treatment units U1 to U4, units for carrying out hydrophobictreatment preceding coating of a coating liquid on the substrate,cooling treatment, and heat treatment (bake treatment) after formationof a film on the substrate or the like are assigned, respectively.

The whole operation of example 1 employing this apparatus of forming afilm will be described.

In FIG. 2A to FIG. 2D, flow of treatment of forming a film isschematically shown following the order. An wafer W prior to treatmentwhich is taken out of the inside of a cassette C of a cassette stage CSby a main arm 13 is stored in a coating unit 2. And, in the coating unit2, a coating liquid T id dripped on a surface of the wafer W (FIG. 2A).As a coating liquid, one in which colloids and/or particles of TEOS, forinstance, is dispersed in a solvent containing ethylene glycol, ethylalcohol, water and a trace of hydrochloric acid can be employed.

Subsequently, the inside of the coating unit 2 is filled with vapor ofthe solvent, ethylene glycol, for instance. In this state, when thewafer W is rotated with high speed, the coating liquid is spread over asurface of the wafer to form a coated film F (FIG. 2B).

Then, the wafer W is disposed on a heating plate 31 of the aging unit 3,followed by closing of a cover 33 to seal. At this time, the wafer W isheated to a predetermined temperature, approximately 100° C., forinstance, by the heating plate 31. Thereafter, vapor of ethylene glycoland a carrier gas are introduced into the aging unit 3 to gel the coatedfilm (FIG. 2C).

Then, in the solvent replacement unit 4, with ethyl alcohol, HMDS(hexamethyl disilane) and heptane, solvent replacement of a gelled filmis carried out. By this solvent replacement, moisture in the coated filmis replaced by ethyl alcohol. Further, by HMDS, hydroxide groups in thecoated film are removed. Further, the solvent in the coated film isreplaced by heptane. The reason to employ heptane exists in that, due touse of a solvent of lower surface tension, stress added on a porousstructure, that is, a reticular structure of TEOS, can be reduced.Thereby, the reticular structure is prevented from collapsing. The stateup to this step is illustrated in FIG. 2D. Thereafter, the wafer W isprocessed for approximately 1 min., for instance, at a bake unit. Thus,on the surface of the wafer W, an interlayer insulating film consistingof silicon oxide film of a thickness of 6000A, for instance, is formed.

In FIG. 3, one example of the aging unit (gelling treatment portion) 3and a gas feeding means 5, both of which are essential portions of thepresent example, is shown. As shown in FIG. 3, the gas feeding means 5is connected to a gas introducing path 34 of the aging unit 3.

The gas feeding means comprises a gas mass flow controller 51, a liquidmass flow controller 52, a vaporizer 53, a 3-way valve 54 and pipes ortubes connecting them.

The gas mass flow controller 51 controls flow rate of the carrier gasconsisting of a nitrogen gas or an ammonia gas delivered from a carriergas feeding device (not shown in the figure).

The liquid mass flow controller 52 controls the flow rate of the solventsuch as ethylene glycol delivered from a solvent dispensing device (notshown in the figure).

A vaporizer 53 vaporizes the solvent controlled in flow rate by the gasmass flow controller 51 and the liquid mass flow controller 52.

The 3-way valve 54 switches the direction of delivery of the gascontaining vapor of the solvent component vaporized by the vaporizer 53between the chamber side and the exhaust side of the aging unit 3.

The aging unit 3 has a configuration identical with the unit shown inFIG. 11.

Therefore, a detailed description of the aging unit 3 is omitted here.Incidentally, the gas from the gas introducing path 34 is dispersed in adispersing room 34 a and is introduced into a treatment space from a gasintroducing inlet 34 b formed in slit along the circumference direction.

Next, flow of the gelling treatment will be described.

FIG. 4 shows a flow-chart of the gelling treatment. First, a 3-way valve54 is switched toward the exhaust side. Then, a carrier gas and asolvent are supplied from a carrier gas supply device (not shown in thefigure) and a solvent supply device (not shown in the figure),respectively. Then, at the vaporizer 53, a gas mixture of vapor of thesolvent component and the carrier gas is formed. Thus generated gasmixture is exhausted through the 3-way valve 54 (step 1).

When the state of generation such as concentration, temperature or thelike of the gas mixture became stable, in the coating unit 2, the waferW coated thereon a film is placed on the heating plate 31 kept at thepredetermined temperature and the cover 33 is closed (step 2).

Then, the 3-way valve 54 is switched toward the chamber side. For awhile after being switched toward the chamber side, that is, until thegas introducing path 34 of the aging unit 3 and the inside of thetreatment chamber S are filled by the gas mixture, the concentration ofthe solvent component in the gas mixture is adjusted to be the saturatedconcentration at the treatment temperature, for instance, 100° C. (timeA in FIG. 5).

Then, after the temperature of the wafer W is raised gradually from thenormal temperature to fill the insides of the treatment chamber S by thegas mixture, until the temperature of the wafer W reaches thepre-determined temperature To, for instance, 100° C., the averageconcentration of the solvent component in the gas mixture is made low(time B in FIG. 5). During the period where the solvent concentration islow, the concentration of the solvent component is continuously raisedas the wafer temperature is elevated. The concentration of the solventcomponent is preferably controlled such that the partial pressure of thesolvent component is always equal with the saturated vapor pressure atthe wafer temperature, that is, 100% (step S3).

Incidentally, the concentration control of the solvent component may becarried out by controlling the flow rate of the carrier gas with the gasmass flow controller 51. Or, it can be carried out through control ofthe liquid mass flow controller 52. Further, both of them may beemployed simultaneously.

When the temperature of the wafer W attained the predeterminedtemperature, the concentration of the solvent component is controlled tobe the saturated concentration (100%) (step 4). Then, this state ismaintained until gelling treatment of the coated film is completed (timeC in FIG. 5). Thereafter, by switching the 3-way valve 54 toward theexhaust side, the gas mixture sent from the vaporizer 53 is exhausted(step S5). Then, by opening the cover 33 of the aging unit 3, the waferW is carried out of the aging unit 3 (step 6). Thereby, the gellingtreatment is completed.

According to the example 1, since, after the state of generation of thegas mixture became stable, the gas mixture is supplied into a sealedcontainer of the aging unit 3, at the start of gas introduction,fluctuation of the concentration and the temperature of the solventcomponent can be suppressed. Further, until the temperature of the waferis elevated to the pre-determined temperature after the wafer is carriedinto the sealed container, the gas concentration of the solventcomponent in the gas mixture is gradually elevated corresponding to thetemperature of the wafer. Therefore, the gas of the solvent componentcan be prevented from condensing immediately after carrying in of thewafer W into the sealed container, thereby excellent thin film such asan interlayer insulating film can be obtained.

In FIG. 6, another example of the gas feeding means is illustrated. Asshown in FIG. 6, the gas feeding means 6 comprises a gas mass flowcontroller 61, a 2-way valve 62, a chamber 63, a heater 64, a feedingpipe 65, a gas mass flow controller 66, a 2-way valve 66 a, a 2-wayvalve 67, and pipes or tubes connecting therebetween.

The gas mass flow controller 61 controls the flow rate of the carriergas consisting of a nitrogen gas, an ammonia gas or the like fed fromthe carrier gas feeder (not shown in the figure).

The 2-way valve 62 switches feeding or stoppage of the carrier gasregulated in flow rate by the gas mass flow controller 61 to a chamberof the aging unit 3.

The container 63 stores the solvent such as ethylene glycol or the like.

The heater 64 heats the solvent.

The feeding pipe 65 is to pass a bubbling gas such as a nitrogen gas (N₂gas) fed from the bubbling gas feeder (not shown in the figure) into thesolvent such as ethylene glycol solution.

The gas mass flow controller 66 is to control the flow rate of thesolvent vapor generated by a container 63 which is a heating bubbler.

The 2-way valve 66 a is to carry out switching between feed and stoppageof the solvent vapor controlled in flow rate by the mass flow controller66.

The 2-way valve 67 switches exhaust and stoppage of the solvent vaporgenerated by the heating bubbler.

The carrier gas and the solvent vapor are fed into the chamber 3 aftermixing.

In the case of the gas feeding means shown in FIG. 6 being employed, atthe same time with opening of the 2-way valves 62 and 66 a, the 2-wayvalve 67 of the solvent vapor line is closed, for instance, and, byoperating either one or both of the mass flow controllers 61, 66, theconcentration of the solvent component in the gas mixture can be variedcontinuously. However, if the flow rate of the bubbling gas (N₂) is heldconstant, while exhausting the vapor by opening the 2-way valve 67, onlythe necessary flow rate may be flowed by controlling the mass flowcontroller 66. In this case, the pressure in the container 63 isadvantageously stabilized. Further, by opening the 2-way valve 67 of thesolvent vapor line and by squeezing the 2-way valve 66 a to make zerothe flow rate, feed of the solvent vapor to the chamber 3 can bestopped. Incidentally, if the mass flow controllers 61, 66 have acomplete shut-off function, 2-way valves 62 and 66 a can be dispensedwith.

And, also in the example illustrated in FIG. 6, the concentration of thesolvent component in the gas mixture can be continuously controlledcorresponding to the wafer temperature. As illustrated in theaforementioned FIG. 5, for instance, the concentration of ethyleneglycol is controlled. Further, before the wafer W is carried in, asidentical as the aforementioned example, the solvent vapor of ethyleneglycol is kept being generated and exhausted. Therefore, upon startinggas introduction, fluctuation of the temperature and the concentrationof the solvent component can be suppressed, in addition, condensation ofthe gas of the solvent component due to low temperature of the wafer isprevented from occurring, thus, the excellent thin film such as aninterlayer insulating film can be obtained.

Further, the gas feeding means 7 shown in FIG. 7 is one in which themass flow controller 61 of the carrier gas line is omitted from the gasfeeding means 6 shown in FIG. 6. Other constitution is identical as thegas feeding means 6 shown in FIG. 6.

In this case, in order to control the concentration of the solventcomponent in the gas mixture, in a state where the 2-way valve 62 of thecarrier gas line is opened and the flow rate of the solvent component iscontrolled by the mass flow controller 66, opening/closing of the 2-wayvalve 67 of the solvent vapor line may only be switched appropriately.

That is, as shown in FIG. 8, until the wafer W is carried in the chamber3 and, after the inside of the gas introducing path 34 and the treatmentchamber S are filled with the gas mixture, the temperature of the waferis elevated to the pre-determined temperature, for instance,approximately 100° C. (time B in FIG. 8), the 2-way valve 67 is switchedto the chamber 3 side intermittently. Thereby, the time-averagedconcentration of the solvent component in the gas atmosphere in thechamber 3 can be adjusted. This time, in the time interval B as shown inFIG. 8, by making relatively and gradually longer the timings ofswitching of the 2-way valve 67 toward the chamber 3 side, the averageconcentration of the solvent component in the gas atmosphere in thechamber 3 can be controlled to be an appropriate concentrationcorresponding to the elevation of the wafer temperature. Incidentally,in FIG. 8, conductance of the gas flow path is ignored and depiction ismade by assuming that the concentration of the gas varies correspondingto the switching of the valve 67.

In this case also, before carrying in of the wafer W, it is preferablethe solvent vapor to be kept being generated and exhausted. Also in thisexample, fluctuation of the concentration and the temperature of thesolvent component can be suppressed at the start of gas introduction,further, condensation of the gas of the solvent component due to thewafer of low temperature can be prevented from occurring. Thereby, anexcellent thin film such as an interlayer insulating film can beobtained. Further, in the example shown in FIG. 7, by disposing atemperature controlled buffer room 71, the concentration fluctuation ofthe solvent vapor can be averaged.

Further, the gas feeding means 8 shown in FIG. 9, in the gas feedingmeans 7 shown in FIG. 7, in place of the mass flow controller 66 and the2-way valve 67, is provided with a 3-way valve 81 which flows thesolvent vapor to any one of the chamber 3 side and the exhaust side. Byswitching appropriately the feeding direction of the solvent vaporbetween the chamber 3 side and the exhaust side, the solvent vapor canbe intermittently fed to the chamber 3 as shown in FIG. 8. Thereby, theconcentration of the solvent component in the gas atmosphere in thechamber 3 can be controlled such that the appropriate concentrationcorresponding to the temperature rise of the wafer is attained.

Incidentally, in all of FIGS. 3, 6, and 7, from generation of thesolvent vapor to the chamber, the piping can be heated with an object toprevent condensation in the piping from occurring.

In the above, in the first invention, the means for generating thesolvent vapor is not restricted to a heating bubbler. Further, in thegas feeding means 6 and 7 shown in FIG. 6 and FIG. 7, the carrier gasline is dispensed with. In the case where there is no carrier gas line,at the heating bubbler, the solvent concentration and the flow rate ofthe bubbling gas may be controlled. Further, as the substrate to besubjected to treatment, without restricting to the wafer, the glasssubstrate for liquid crystal display can be employed.

Thus, according to the first invention, fluctuation of the concentrationand the temperature of the solvent component can be suppressed at thebeginning of gas introduction. Further, condensation of the gas of thesolvent component can be prevented from occurring immediately aftercarrying in the substrate, thereby the excellent thin film such as theinterlayer insulating film can be obtained.

In the following, Example 2 involving the second invention will bedescribed. Incidentally, in the following examples, the parts repeatingthe preceding examples are omitted from explanation.

EXAMPLE 2

In such an apparatus of forming a film as shown in FIG. 1, the wafer W,after being subjected to hydrophobic treatment and cooling treatment, issequentially carried to the coating unit 2, aging unit 3, and solventreplacement unit 4 by the main arm 13, and, after being carried outrespective pre-determined treatments at these units, bake treatment iscarried out.

The steps of forming a film and gelling carried out at the coating unit2 and the aging unit 3, respectively, will be briefly described withreference to FIG. 2A to FIG. 2D.

In the step of forming a film, in order to suppress vaporization of thesolvent in the coating liquid, in the not shown treatment chamber filledwith the vapor of ethylene glycol for instance, on the approximatelyrotation center portion on the surface of the wafer W sucked to the spinchuck 21, the coating liquid T is fed (FIG. 2A). Next, by rotating thewafer W, the coating liquid T is spread over the whole surface of thewafer due to the centrifugal force to form a film (FIG. 2B). Here, thecoating liquid T is one in which colloids or particles of TEOS which isa metal alkoxide are dispersed in solvent such as ethylene glycol orethyl alcohol, for instance, and water and a trace of hydrochloric acidare further contained.

Further, in the gelling step, the colloids of TEOS contained in thecoated film on the wafer is gelled to link the colloids in reticulum.Therefore, in the treatment chamber filled by vapor of ethylene glycol,the wafer W is heated to approximately 100° C. by the heating plate(FIG. 2C) Here, introduction of the vapor of ethylene glycol into thetreatment chamber is carried out to suppress vaporization of the solventin the coated film. Therefore, it is controlled such that, at thetemperature in the treatment chamber, for instance, the vapor pressurebecomes 100%.

In this gelling step, instead of heating, by carrying out the treatmentat normal temperature in the treatment chamber filled by an ammonia gas,by use of the ammonia gas which is an alkali catalyst, gelling of thecolloids of TEOS may be expedited.

Subsequently, the solvent replacement unit 4 will be described withreference to the side view of a profile of FIG. 12 and the plan view ofFIG. 13. In the figure, reference numeral 131 denotes a chuck of holdingan wafer W in a level position (an approximate level position can beincluded). This chuck 131 is constituted by a vacuum chuck for instanceand sucks and holds the wafer W. To the approximately central portion ofthe bottom surface of the chuck 131, a rotation axis 133 capable ofbeing gone up and down and rotated by a driving portion 132 is attached.With such a configuration, the chuck 131 is capable of going up and downbetween a delivering position of the wafer W which is shown by thedotted line in the figure and is positioned above a cup to be describedlater and a treatment position of the wafer W shown by the solid line inthe figure. Further, the chuck 131 is designed to be rotated around avertical axis.

In the circumference of the chuck 131 which is in the treatment positionand the wafer W, a cup 134 is disposed to in order to surround these. Onthe upper surface of this cup 134, an opening 134 a where the wafer W ispassable is formed. The opening 134 a can be opened and closed by acover 135 which is disposed such that it is capable of going up anddown. Further, at the bottom portion of the cup 134, a liquid exhaustpath 136 a and an exhaust gas path 136 b are connected.

Inside the cup 134, above the outside of the wafer W when the chuck 131holding the wafer W is in a treatment position, for instance, 3 nozzlesof 140A through 140C are disposed.

Among these nozzles 140A to 140C, 140A is the first nozzle of dispensingalcohol such as ethanol on the surface of the wafer W. Similarly, 140Bis the second nozzle of dispensing a hydrophobic treatment liquid suchas HMDS. Further, the nozzle 140C is the third nozzle of dispensing asolvent such as heptane of smaller surface tension than the solventcontained in the coating liquid. These nozzles 140A through 140C aredisposed with the same distance apart in the circumference direction asshown in FIG. 13. These nozzles 140A through 140C correspond to therespective solvent dispensing portions of the present invention.

These nozzles 140 (140A through 140C) are attached to the inside wall ofthe cup 134 with the respective attachments 141, and the tip end of eachnozzle is attached slantingly to be directed toward the approximatelycenter of rotation O of the surface of the wafer W (the surface thereona coated film is formed). Therewith, from each nozzle 140, as shown inthe figure with the dotted lines, the solvent is dispensed around thecenter of rotation O of the surface of the wafer W. Further, the tipends of these nozzles are positioned outside the wafer W held by thechuck 131. Therefore, when the chuck 131 which holds the wafer W goes upand down, the wafer W and the each nozzle 140 are designed not tointerfere each other.

The respective nozzles 140 are connected respectively to the ethanoltank 143 a, HMDS tank 143 b, and heptane tank 143 c (not shown in FIG.12) which are disposed outside the cup 134 by the solvent dispensingpath 142 (142 a through 142 c) inserted from the bottom surface of thecup 134, for instance. The solvent dispensing paths 142 a through 142 care provided respectively with valves Va through Vc. These valves Vathrough Vc are controlled in their timings of opening and closing andthe degree of opening by a controller 144.

In this solvent replacement unit 4, the step of solvent replacement iscarried out as follows. That is, the cover 135 is elevated up to theposition shown by the dotted line in FIG. 12. At the same time, thechuck 131 is elevated up to the position above the cup 134. Then, at theposition shown by the dotted line in FIG. 12, by the main arm 13, thewafer W carried up to the unit 4 is delivered to the chuck 131. Then,the chuck 131 is lowered down to the treatment position. At the sametime, the cover 135 is lowered down to close the cup 134. Thereafter,the wafer W is rotated. Subsequently, with the controller 144, the valveVa is opened, thereby ethanol is dispensed around the center of rotationO of the surface of the wafer W from the first nozzle 140A. Due tocentrifugal force, the ethanol diffuses over the whole surface of thewafer W. Thereby, ethanol dissolves in the moisture in the coated film.As the result, the moisture is replaced by the ethanol. Incidentally,preceding the rotation of the wafer W, ethanol may be dispensed aroundthe center of rotation O of the surface of the wafer W.

After thus ethanol is dispensed on the surface of the wafer W, whilerotating the wafer W, similarly the valve Vb is opened. Thereby, HMDS isdispensed on the surface of the wafer W from the second nozzle 140B tomake diffuse. Thereby, hydroxide groups in the coated film are removed.Further thereafter, the valve Vc is opened to dispense heptane on thesurface of the wafer W from the third nozzle 140C to make diffuse.Thereby, the solvent in the coated film is replaced by heptane. Thereason why to use heptane is to reduce the force added on the porousstructure namely reticular structure of TEOS by use of the solvent oflower surface tension, thereby the reticular structure of TEOS isprevented from collapsing.

Here, the timings of opening and closing of each valve Va, VB and Vc areshown in FIG. 14. That is, immediately before closing the valve Va, thevalve Vb is opened, further, immediately before closing the valve Vb,the valve Vc is opened. That is, immediately before supply of ethanolcompletes, supply of HMDS is began. Similarly, immediately before supplyof HMDS completes, supply of heptane is started. Thus, it is designedsuch that a state in which supply of the solvent is stopped does notoccur when the solvent to be dispensed to the wafer W is switched. Here,when 2 kinds of the solvents are being dispensed simultaneously, byreducing the degree of opening of the valve of the solvent of whichsupply is to be stopped, the flow rate of the solvent may be reduced.

Thus, the wafer W undergone the predetermined treatment at the solventreplacement unit 4 is carried up to the bake unit by the main arm 13.The wafer W is bake treated at this unit, thereby on the surface of thewafer W, an interlayer insulating film consisting of a silicon oxidefilm is formed.

According to the aforementioned example 2, since 3 pieces of nozzles 104corresponding to 3 kinds of solvents are attached inside the cup 134,without implementing opening and closing of the cover 135 and movementof the nozzles 140, the solvent can be dispensed on the surface of thewafer W. Therefore, when the solvent to be dispensed to the wafer W isswitched, before stopping the supply of the preceding solvent, supply ofthe succeeding solvent is began, thereby a state in which both solventsare dispensed simultaneously can be realized. Thus, since the solventscan be fed continuously, there is no time when the supply of the solventis interrupted.

Thereby, inconvenient phenomena occurring due to interruption of supplyof the solvent, that is, the phenomena such that, due to contact of thesolvent on the surface of the wafer and air, the moisture in the air isconfined in the coated film, or, the solvents vaporize, can be preventedfrom occurring in advance. As the result, the film structure of TEOS canbe prevented from collapsing, an excellent silicon oxide film can beformed on the wafer W.

Further, in the example 2, the solvents can be dispensed continuously.Therefore, in the case of the preceding solvents being replaced,compared with the conventional method where opening and closing of thecover and transfer operation of the carrying arm are necessary, the timenecessary for the whole solvent replacement treatment can be maderemarkably short, and the throughput of the whole treatment can beimproved. Further, thus, the time necessary for the solvent replacementstep can be made short. As the result, the time period during which thelarge surface tension of the solvent is added on the reticular structureof TEOS is made short. Therefore, also from this point of view, the filmis suppressed from collapsing.

In the above example 2, upon dispensing ethanol, HMDS, and heptane,stoppage of supply of the preceding solvent and start of supply of thesucceeding solvent may be carried out simultaneously. Further, by makingextremely short the time period between the stoppage of supply of thepreceding solvent and the start of supply of the succeeding solvent,supply of the both solvents may be carried out continuously withoutessentially being interrupted. Even in such a case, supply of thepreceding solvent and the succeeding solvent is carried out withoutessentially being interrupted. As the result, the aforementionedinconvenient phenomena can be suppressed from occurring, thus anexcellent thin film can be formed on the substrate.

EXAMPLE 3

Next, another example of a solvent replacement unit for carrying out thesolvent replacement step, that is, example 3 will be described withreference to FIGS. 15 and 16.

The different point of this solvent replacement unit from theaforementioned solvent replacement unit exists in that 3 kinds ofsolvents are dispensed on the surface of the wafer through a commonsolvent dispensing portion 150 arranged in a ring. The solventdispensing portion 150 is disposed inside the cup 134 and at the upperside of the outside of the wafer W when the chuck 131 holding the waferW is positioned at the treatment position, for instance. That is, thesolvent dispensing portion 150 arranged in a ring are t0 fixed to aplurality of places of the inside of the cup 134 through the attachmentmembers 151.

The inside of the solvent dispensing portion 150 is disposed slantedwith an expanding diameter toward, for instance, the lower side. On thisslanting surface, a plurality of dispensing holes 152 are formed along acircumference direction with an equal distance apart. Thereby, thesolvent from the respective dispensing hole 152 is dispensed on aroundthe center of rotation O of the surface of the wafer W. Further, theinside of the solvent dispensing portion 150 is positioned outside thewafer W held by the chuck 131. Therefore, when the chuck 131 holding thewafer W went up and down, the wafer W and the solvent dispensing portion150 are designed not to interfere each other.

To this solvent dispensing portion 150, one end side of the solventdispensing path 153 inserted from, for instance, the bottom surface ofthe cup 134 is connected. On the other hand, the other end side of thesolvent dispensing portion 153 are branched, outside the cup 134, forinstance, into 3 dispensing paths 153 a through 153 c. The other endsides of these branched dispensing paths 153 a through 153 c areconnected to a ethanol tank 154 a, a HMDS tank 154 b, and a heptane tank154 c, respectively. To the branched dispensing paths 153 a through 153c, valves Va through Vc are inserted, respectively. The timing ofopening or closing and the degree of opening of these valves Va throughVc are controlled by a controller 144. Other configuration is identicalas the aforementioned example 2.

In this solvent replacement unit 4, after the wafer W is held by thechuck 131, the cup 134 is closed. Thereafter, the valve Va is opened bythe controller 144, ethanol is dispensed to the solvent dispensingportion 150 through the solvent dispensing paths 153 a and 153. Then,ethanol is dispensed in the neighbor of the center of rotation O on thesurface of the wafer W through the dispensing holes 152 from the solventdispensing portion 150. Then, as identical as the aforementionedembodiments, ethanol is diffused all over the whole surface of the waferW.

Then, by opening the valve Vb, HMDS is dispensed on the surface of thewafer W through the solvent dispensing paths 153 b, 153, and the solventdispensing portion 150. Subsequently, by opening the valve Vc, heptaneis dispensed on the surface of the wafer W through the solventdispensing paths 153 c, 153, and the solvent dispensing portion 150. Inthis case, the timings of opening and closing of the valves Va, Vb, andVc are carried out identical as the above example 2.

EXAMPLE 4

Subsequently, still another example of the solvent replacement unit forcarrying out the step of solvent replacement, that is, Example 4, willbe described with reference to FIG. 17. The different point of thissolvent replacement unit from the aforementioned solvent replacementunit exists in that 3 kinds of solvents are dispensed on the surface ofthe wafer through a common solvent nozzle 160.

The solvent nozzle 160 is disposed combined with the cover 135 in such amanner that the tip end of the nozzle 160 pierces through the cover 135of the cup 134 to oppose the neighborhood of the center of rotation onthe surface of the wafer W. Thereby, the solvent is ejected in theneighborhood of the center of rotation of the surface of the wafer W. Inthis example, the solvent nozzle 160 corresponds to a common solventdispensing portion.

To this solvent nozzle 160, one end side of the solvent dispensing path161 is connected. On the other hand, the other end side of the solventdispensing path 161 is branched into 3 dispensing paths 161 a, 161 b,and 161 c. The other end sides of these branched dispensing paths 161 athrough 161 c are connected to a ethanol tank 162 a, a HMDS tank 162 b,and a heptane tank 162 c.

Further, in the branched dispensing paths 161 a through 161 c, valves Vathrough Vc are inserted, respectively. These valves Va through Vc arecontrolled of their timings of opening and closing and their degree ofopening through a controller 144. The other configuration is identicalas that of the aforementioned example.

In this example 4, after the wafer W is held by the chuck 131, the cup134 is closed. Thereafter, the valve Va is opened by the controller 144,ethanol is dispensed in the neighborhood of the center of rotation O ofthe surface of the wafer W through the solvent dispensing portions 161 aand 161 b, and the solvent nozzle 160. Then, upon the valve Vb beingopened, HMDS is dispensed on the surface of the wafer W through thesolvent dispensing paths 161 b and 161, and the solvent nozzle 160.Subsequently, upon the valve Vc being opened, heptane is dispensed onthe surface of the wafer W through the solvent dispensing paths 161 cand 161, and the solvent nozzle 160. Here, the timings of opening andclosing of the valves Va, Vb, and Vc are identical as the example 2.

Even in the solvent dispensing units shown in these FIG. 15 and FIG. 17,ethanol, HMDS, and heptane are continuously dispensed on the surface ofthe wafer W in this order through the common solvent dispensing portion150 or the nozzle 160. Therefore, the effect identical as the case inwhich the solvent replacement unit shown in FIG. 12 is employed can beobtained. Further, the solvent dispensing portion shown in FIG. 15 andthe solvent nozzle 160 shown in FIG. 17 may be combined. That is, amongthe solvent dispensed through the solvent dispensing portion 150,dispensing deficiency in the neighborhood of the center of rotation ofthe wafer W may be complemented by the supply due to the solvent nozzle160.

According to the second invention, in the method of forming a filmhaving a step of carrying out replacement of the solvent by dispensing aplurality of solvents on the substrate, the preceding solvent and thesucceeding solvent can be dispensed continuously. As the result, anexcellent thin film such as an interlayer insulating film can beobtained.

EXAMPLE 5

Next, Example 5 involving the third invention of the present applicationwill be described.

In FIG. 19, an example of a coating unit 2 involving the third inventionis illustrated.

As shown in FIG. 19, the coating unit 2 comprises a cup 22 which is atreatment chamber, a vacuum chuck 25 which is disposed inside the cup 22and functions as a rotary stage holding the wafer, and a coating liquidnozzle 26 for dispensing the coating liquid on the center portion of thewafer W.

On the upper surface of the cup 22, an open inlet for carrying in asubstrate 22 a is disposed. This intake for taking in the substrate 22 ais opened and closed by a cover 21 capable of freely going up or down.At the bottom surface of the cup 22, a breakthrough 22 b is disposed.From this breakthrough 22 b, a rotation axis 24 is inserted. The upperend of the rotation axis 24 is combined with the vacuum chuck 25, thelower end of the rotation axis is combined with a driving portion 23.Rotating driving force of the driving portion 23 is transmitted to thevacuum chuck 25 through the rotation axis 24. Further, the rotation axis24 is designed to be capable of going up or down.

To the cover 21, a coating liquid nozzle 26 of dispensing coating liquidon the center portion of the wafer W is attached.

To the cup 22, solvent vapor dispensing pipes 27 for dispensing vapor ofthe solvent employed in the coating liquid are connected. On the baseside of the solvent vapor dispensing pipe 27, a solvent vapor generator27 a is connected. These solvent vapor dispensing pipes 27 are disposedsuch that the solvent vapor is dispensed into the cup 22 from a positionhigher than, for instance, the wafer W disposed on the pre-determinedposition in the cup 22. Further, as shown in FIG. 20, the pipes aredisposed in the cup 22 such that the solvent vapor can be dispensed fromthe both sides of the wafer W.

Further, at the bottom surface and the cover 21 of the cup 22, as shownin FIG. 19, the solvent nozzles 262 and 263 for dispensing the solvent,which is a cleaning agent for removing (edge-rinse treatment) the coatedfilm at the circumference portion of the wafer, from the solventdispensing source 261, are inserted. The solvent nozzle 263 disposed onthe cover 21 is to eject the solvent toward the circumference on thesurface side of the wafer W. The solvent nozzle 262 disposed on the cup22 is to remove the coating liquid which goes around the rear surface ofthe wafer by ejecting the solvent toward the circumference of the rearsurface side of the wafer W.

Further, to the cup 22, a drain pipe 28, an exhaust pipe 29 areconnected. There is a switching valve 29 a in the mid-way of the exhaustpipe 29.

Then, the treatment of coating a coating liquid on an wafer W accordingto the method of the third invention will be described following order.First, the wafer W is carried to the coating unit 2 by the main arm 13.The carried wafer W is delivered to the chuck 25 at the position of thedotted line in FIG. 19, for instance. That state is shown in FIG. 21A.Subsequently, after the chuck 25 is lowered, the cup 22 is sealed withthe cover 21. The coating liquid employed here is one in which colloidsor particles of TEOS, which is a metal alkoxide, is dispersed in asolvent containing an organic solvent such as ethylene glycol and ethylalcohol and further water and a trace of hydrochloric acid.

Ethylene glycol is employed to adjust the viscosity to the mostappropriate one for coating the coating liquid.

Further, other than viscosity adjustment, because of low vapor pressureof ethylene glycol, it can be employed with an object to preventshrinkage of the film due to volatilization of the solvent in the agingstep from occurring.

And, in this example, as shown in FIG. 21B, while exhausting from theexhaust pipe 29, for instance, vapor of ethylene glycol 260 is dispensedinside the cup 22 from the solvent vapor dispensing pipe 27. Then, afterthe inside of the cup 22 is filled by the vapor 260, the exhaust isstopped. The solvent vapor 260 inside the cup 22 at this time isdesirable to be the saturated vapor pressure. The reason for this isthat, when the vapor pressure is lower than the saturated vaporpressure, the solvent vaporizes from the coating liquid. On the otherhand, it is because that, when the vapor pressure is higher than thesaturated vapor pressure, that is, when the vapor pressure is in asupersaturated state, the solvent condenses.

Subsequently, as shown in FIG. 21C, the coating liquid S is dispensed onthe center portion of the wafer W from the nozzle 26. Then, as shown inFIG. 22A, by rotating the wafer W with high speed by the chuck 25, thecoating liquid is spread over the surface of the wafer W due tocentrifugal force, to form a coated film. Thereafter, the rotation speedis lowered and, as shown in FIG. 22B, the solvent is sprayed onto thebrim of the wafer W from the nozzles 262 and 263. Thereby, as shown inFIG. 23, the brim portion f of the coated film F spread over the surfaceof the wafer W is removed. Thus, due to removal of the coated film atthe brim portion of the wafer, since the carrying arm and the coatingliquid do not make contact during transfer of the coated wafer W, thearm is prevented from being contaminated by the coating liquid. Further,when the wafer W is carried to the carrier after completion of theprocess, particles caused to peel from a part of the coated film due togroove of the carrier are prevented from occurring. Even in this edgerinse-treatment, the inside of the cup 22 is being filled by the solventvapor 260.

Thereafter, as shown in FIG. 22C, while holding up the cover 21 a littleand letting in air into the cup 22, exhaust from the exhaust pipe 29 iscarried out. Thus, the inside of the cup 22 is replaced by the airatmosphere. Then, by elevating the cover 21 and the chuck 25, the waferW is delivered to the arm for carrying the wafer from the chuck 25.Thereafter, the wafer is carried to the gelling step.

The treatment after gelling step will be described briefly. In thegelling step, as shown in FIG. 24A, after disposing the wafer W on theheating plate 71, the cover 72 is put on to form a sealed space. Thus,the wafer W is heated to a temperature of, for instance, 100° C. toexpedite the aforementioned gelling. In this case, the saturated vaporof ethylene glycol is introduced from the gas introducing path 73 laidinside the heating plate 71, for instance, and is exhausted from theexhaust path 74. Incidentally, this gelling step may be carried out byintroducing basic gas such as ammonia gas into the treatment chamber.

Thereafter, with the identical device as that employed in the coatingtreatment for instance, as shown in FIG. 24B, the wafer W is placed onthe spin chuck 75, on the surface thereof, ethanol and HMDS (hexamethyldisilane) are dispensed in this order. Thereby, moisture and OH groupsare removed. Subsequently, by dispensing a liquid of low surface tensionsuch as heptane, the replacement of the solvent is carried out.Thereafter, the wafer W is treated in the bake step to form a poroussilicon oxide film.

According to the example 5, by filling the inside of the cup 22 by thevapor of ethylene glycol during coating treatment and edge rinsetreatment, the solvent can be suppressed in vaporization from the coatedfilm. As the result, gelling is not hindered, and the pre-determinedthickness can be secured. Incidentally, the edge rinse treatment may becarried out at a different place from the cup 22.

Here, when the spin coating is carried out as described above, at leastduring the wafer W is revolving, the inside of the cup 22 is required tobe filled with the vapor of the solvent. In that case, the nozzle can bedisposed different from the cup 22, for instance. Then, after thecoating liquid is dripped on the wafer W from the nozzle, the cover isclosed and the solvent vapor is dispensed into the cup 22. This is alsoincluded in the third invention.

Incidentally, in order to dispense into the cup 22 by switching thevapor of the solvent and the atmosphere, as shown in FIG. 25, at themidway of the solvent vapor dispensing pipe 27, a 3-way valve 264 oneend thereof is open to the atmosphere may be disposed. Thereby, byswitching the 3-way valve 264 toward the flow side of the atmosphere,while introducing the atmosphere into the cup 22 after coating, theinside of the cup 22 can be exhausted. By connecting the aforementionedone end of the 3-way valve 264 to a nitrogen gas source, nitrogen gascan be dispensed instead of the atmosphere.

In the third invention described above, the solvent vapor dispensingpipe 27 can be disposed such that the vapor of the solvent can bedispensed into the cup 22 from 3 or more directions, for instance.Further, by employing an open end cup and by surrounding it by an airtight vessel, the inside thereof is made an atmosphere of the vapor ofthe solvent and coating may be carried out therein. Further, the edgerinse treatment can be carried out in the open atmosphere, and thecoating can be carried out with a method other than the spin coat.Further, as the substrate to be treated, without restricting to thewafer, glass substrates for liquid crystal displays may be employed.

As described above, according to the third invention, since the coatingliquid in which colloids or particles of the starting substances of thefilm component are dispersed in the solvent can be coated on thesubstrate while preventing the solvent from evaporating, the excellentthin film such as the interlayer insulating film can be obtained.

Further, since the coated film at the brim portion of the substrate isremoved in the atmosphere of the vapor of the solvent, vaporization ofthe solvent of the coating liquid can be suppressed further more.

EXAMPLE 6

Next, example 6 involving the fourth invention will be described.

FIG. 26 is a side view of a profile of the coating unit 2 involvingexample 6.

In the figure, reference numeral 331 denotes a chuck holding an wafer Win level (includes a state which is approximately level). This chuck 331is composed of a vacuum chuck, for instance, and is designed to suck andhold the rear surface side of the wafer W. At the approximate center ofthe bottom surface of the chuck 331, a rotation axis 333 capable ofgoing up and down and rotating by a driving portion 332 is attached.Thereby, the chuck 331 is going up and down between a deliveringposition of the wafer W above the cup which is shown in the figure bythe dotted line and will be described later and a treatment position ofthe wafer W shown in the figure by the solid line. Further, the chuck331 is capable of revolving around a vertical axis.

In the circumference of the chuck 331 and the wafer W which are in thetreatment position, a cup 340 is disposed to surround these. On theupper surface of the cup 340, an opening 341 through which the wafer Wis passable is formed. This opening 341 is opened or closed by a cover342 disposed so as to be capable of going up and down. Further, on theside wall portion of the cup 340, a solvent vapor dispensing pipe 351for dispensing the vapor of the solvent component such as ethyleneglycol, which is employed in the coating liquid X and will be describedlater, into the cup 340 is connected. Further, the vapor of ethyleneglycol is generated at the solvent vapor source 352. Further, at thebottom of the cup 340, a drain pipe 353 and an exhaust pipe 354 areconnected.

At the cover 342, a coating liquid nozzle 361 for dispensing the coatingliquid X approximately on the rotation center of the surface of thewafer (the surface thereon the coated film is formed) and a coatingliquid nozzle 362 for dispensing the solution S approximately on therotation center of the surface of the wafer are disposed. These nozzles361 and 362 are attached slanted combined with the cover 342 such thatthe respective tip end directs toward the approximate center of rotationon the surface of the wafer.

Now, the coating liquid X will be described. In this coating liquid X,colloids or particles of a metal alkoxide such as TEOS which is astarting component are dispersed in a solvent, and, for the solvent,ethylene glycol, ethyl alcohol, water and a trace of hydrochloric acidare employed. An example of the ratio of the respective components inthe coating liquid is as follows. For instance, TEOS and water areemployed in an equal molar ratio, and ethylene glycol solution andethanol solution are employed in several times of water by the molarratio.

Further, the solution S dispensed on the surface of the wafer from thesolution nozzle 62 is preferable to be a solution of smaller viscositythan that of the component of the highest viscosity in the components ofthe solvent of the coating liquid X, and to be capable of dissolving themetal alkoxide and water. Here, the component of the highest viscosityof the components of the solvent of the coating liquid X is ethyleneglycol. Further, it is known that the metal alkoxide such as TEOS or thelike is generally insoluble in water, whereas is soluble in alcohol andorganic solvent. Therefore, as the solution S capable of being employedin the present example 6, alcohol or organic solvent of smallerviscosity than ethylene glycol can be employed. Among them, ethanol, oneof components of the solvent of the coating liquid X, is particularlydesirable to be employed.

Subsequently, a method involving the fourth invention being carried outat the aforementioned apparatus of forming a film will be described.

In this apparatus of forming a film, the wafer W, after being subjectedto hydrophobic treatment and cooling treatment, is sequentially carriedto a coating unit 2, an aging unit 3, and a solvent replacement unit 4by a main arm 13, and, after the respective predetermined treatments arecarried out at these units, is subjected to bake treatment.

Now, steps of forming a film being carried out in the coating unit 2will be described with reference to FIG. 26 and FIG. 27A through FIG.27D. First, the cover 342 is elevated up to the position of the dottedline in FIG. 26. At the same time, the chuck 331 is elevated up to aposition above the cup 340. Then, at the position of the dotted line inFIG. 26, the wafer W carried to the unit 2 by the main arm 13 isdelivered to the chuck 331. Then, the chuck 331 is lowered to thetreatment position, and the cover 342 is lowered to seal the cup 340.

And, in this example, while exhausting from the exhaust pipe 354 forinstance, ethylene glycol vapor is dispensed into the cup 340 from thesolvent dispensing pipe 351. Then, after the inside of the cup 340 isfilled by the vapor, exhaust is stopped. Then, as shown in FIG. 27A, thesolution S such as 99.9% ethanol solution for instance is dispensed atthe approximate center of rotation of the wafer W from the solutionnozzle 362. Then, as shown in FIG. 27B, the wafer W is rotated by thechuck 331. Thereby, the solution S is diffused over the whole surface ofthe wafer W due to centrifugal force, to spread.

Subsequently, as shown in FIG. 27C, the coating liquid X is dispensed onthe approximate rotation center of the wafer W from the coating liquidnozzle 361. In this case, the coating liquid X is preferable to bedispensed when the coated solution S is in a state where it does notvaporize and exists on the surface of the wafer W.

Then, as shown in FIG. 27D, the wafer W is rotated by the chuck 331, thecoating liquid X is diffused and spread over the whole surface of thewafer due to centrifugal force, to form the coated film.

Incidentally, though not shown in the figure, thereafter, thinner issprayed on the brim portion of the wafer W from a thinner nozzle in thecup 340, thereby the coated film of the brim portion is removed.

Further, in this example, why the inside of the cup 340 is filled by thevapor of ethylene glycol is to suppress vaporization of the solvent inthe coating liquid.

Thereafter, while maintaining a state where the cover 342 is being heldup a little, the inside of the cup 340 is evacuated. Then, by elevatingthe cover 342 and the chuck 331, the wafer W is delivered to thecarrying arm 13 from the chuck 331, and is sequentially transferred tothe aging unit 3 and the solvent replacement unit 4. At the respectiveunits 3 and 4, the gelling step and the solvent replacement step arecarried out. Then, these steps will be described briefly with referenceto FIG. 28A and FIG. 28B.

First, in the gelling step, the treatment of gelling the colloids ofTEOS contained in the coated film on the wafer W is carried out to linkthe colloids in a reticular structure. For this, in a treatment chamber371 filled by the vapor of ethylene glycol, the wafer W is heated toaround 100° C. by the heating plate (FIG. 28A). Here, why the vapor ofethylene glycol is introduced into the treatment chamber 371 is tosuppress vaporization of the solvent in the coated film. Therefore, atthe temperature of, for instance, the inside of the treatment chamber371, vapor is adjusted to be 100%. In this gelling step, instead ofheating, a catalyst such as ammonia can be employed.

In that case, in the treatment chamber 371 filled by an ammonia gas, forinstance, treatment is carried out at normal temperature, the gelling ofthe colloids of TEOS may be expedited by the ammonia gas which is abasic catalyst.

Subsequently, in the solvent replacement step, by dispensingsequentially ethanol, HMDS (hexamethyl disilane) and heptane on theapproximate rotation center of the surface of the wafer W, the solventin the coated film is replaced by another solvent. Therefore, in thesolvent replacement unit 4, as shown in FIG. 28B, the wafer W is held inlevel on the wafer hold 372 constituted to be capable of rotating aroundthe vertical axis. On the other hand, 3 pieces of nozzles 373 (373 a,373 b, 373 c) respectively ejecting ethanol, HMDS, and heptane areprepared. Then, these nozzles 373 (373 a, 373 b, 373 c), by grasping bythe carrying arm 374 and pulling out in turn from the respective nozzlereceivers which are not shown in the figure, are transferred to thecenter portion of the wafer W.

In this step, first, the wafer W is rotated. In this state, ethanol isdripped on the approximate rotation center of the surface of the wafer Wto diffuse over the whole surface of the wafer W due to centrifugalforce.

Thereby, ethanol dissolves in the moisture in the coated film. As theresult, the moisture is replaced by ethanol. Subsequently, whilerotating the wafer W similarly, HMDS is dripped on the surface of thewafer W. Thereby, OH groups in the coated film are removed. Further,heptane is dispensed on the surface of the wafer W. Thereby, the solventin the coated film is replaced by heptane. The reason why to employheptane is that, due to use of a solvent of low surface tension, theforce on a porous structure that is a reticular structure of TEOS can bemade small, and the reticular structure of TEOS is made not to collapse.

The wafer W thereon the predetermined treatment is carried out at thesolvent replacement unit 4 is transferred to the bake unit by the mainarm 13. At this unit, the wafer W is subjected to the bake treatment.Thereby, on the surface of the wafer W, an interlayer insulating filmconsisting of a silicon oxide film is formed.

According to the aforementioned example 6, in the step of forming afilm, prior to coating of the coating liquid, the whole surface of thewafer is coated by ethanol. In a state where the ethanol exists on thesurface of the wafer W, thereon the coating liquid X is dispensed. Here,since the ethanol is lower in viscosity than ethylene glycol, theethanol itself readily diffuses over the whole surface of the wafer.Therefore, the ethanol goes into minute concave/convex portions formedon the surface of the wafer W thoroughly.

Thus, in a state where ethanol exists on the whole surface of the wafer,on the surface of the wafer W, the coating liquid X is dispensed, todiffuse. The components composing the coating liquid X, that is, all ofTEOS, water, ethylene glycol and hydrochloric acid are soluble inethanol. Therefore, the coating liquid X mingles with ethanol on thesurface of the wafer W. As the result, the coating liquid X becomes astate of capable of being mingled with ethanol, thereby goes into theplaces where ethanol exists.

Moreover, ethanol is lower in viscosity than ethylene glycol asmentioned above. Therefore, the coating liquid X mingled with ethanolbecomes low in viscosity and becomes readily diffused. Therefore, whenthe wafer W is rotated, the coating liquid X spreads universally on thewhole surface of the wafer and goes into the minute concave/convexportions. Therefore, all over the surface of the wafer, the coated filmis formed.

In this time, even when, as the coating liquid S, the solution oralcohol which is lower in viscosity than ethylene glycol and dissolvesmetal alkoxide and water is employed, the component of the coatingliquid X and the solution S mingle each other. As the result, theviscosity of the coating liquid X to be spread over the surface of thewafer W becomes low, thereby the similar effect as ethylene glycol canbe obtained.

Further, when, as the solution S, ethanol which is one of solventcomponents of the coating liquid X is employed, since ethanol isincluded as the solvent in advance, mingling of the solution S and thecoating liquid S on the surface of the wafer is proceeded readily.Therefore, during mingling of the solution S and the coating liquid X,there are no generation of bubbles and no remaining thereof in thecoated film. Therefore, a coated film of more excellent quality can beformed.

Now, if a solution of higher viscosity than ethylene glycol had beenemployed, the solution S itself would be difficult to diffuse.Therefore, penetration into the minute concave/convex portions on thesurface of the wafer W becomes difficult. Further, since the viscosityof the coating liquid X after the solution S and the coating liquid Xwere mingled becomes high, the coating liquid X becomes further moredifficult to diffuse. As the result, an even coating of the coatingliquid X on the whole surface of the wafer W becomes difficult.

Further, if a solution in which a metal alkoxide or water does notdissolve is employed as the solution S, the solution S and the coatingliquid X do not mingle. Therefore, the viscosity of the coating liquid Xcan not be made low. Furthermore, because of hindrance of the solution Sto the coating liquid X, coating on the surface of the wafer W can notbe carried out. Incidentally, inclusion of water in the solvent of thecoating liquid is not restricted. However, when water is contained, thesolution is necessary to be capable of dissolving the starting substanceand water.

Thus, according to the aforementioned example 6, a coating liquid Xbecomes capable of being coated easily on the surface of the wafer W,thereby the coating liquid X can be coated on the whole surface of thewafer W universally. Therefore, since formation of the film can besecured all over the whole surface, as the result, a thin film ofexcellent quality such as an interlayer insulating film can be formed.

In the above-mentioned method of forming a film of the fourth invention,the aforementioned solvent replacement step is not always necessary. Bycarrying out gelling step after the step of forming a film, a thin filmsuch as an interlayer insulating film may be formed.

According to the fourth invention, before coating a coating liquid inwhich particles or colloids of a starting substance of a film componentare dispersed in a solvent, a solution of which viscosity is smallerthan that of the component of the highest viscosity among solvents ofthe coating liquid and is capable of dissolving the starting substanceis coated on the surface of the substrate. Thereby, coating of thecoating liquid on the surface of the substrate becomes easy, thereby thefilm can be universally formed over the whole surface of the substrate.As the result, an excellent thin film such as an interlayer insulatingfilm can be obtained.

EXAMPLE 7

Next, example 7 involving the fifth invention of the present applicationwill be described.

FIG. 1 is a plan view showing an apparatus involving example 7.

FIG. 2A through FIG. 2D are diagrams showing schematically each step ofthe method of forming a film involving example 7.

In this apparatus, an wafer W, after being subjected to hydrophobictreatment and cooling treatment, is sequentially transferred to acoating unit 2, an aging unit 3, and a solvent replacement unit 4 by amain arm 13, and at these units, the predetermined treatments arecarried out, respectively.

That is, at the unit 2, as shown in FIG. 2A, on the approximate rotationcenter of the surface of the wafer W sucked and held by an wafer holder21 which will be described later, by the later described coating liquidnozzle 5, a coating liquid X is dispensed. Then, as shown in FIG. 2B, byrotating the wafer W, the coating liquid X is spread over the wholesurface of the wafer W due to centrifugal force to form a film(treatment of forming a film).

Then, at the aging unit 3, colloids of TEOS contained in the coated filmon the wafer W is gelled, treatment thereby to link the colloids to forma reticular structure is carried out (gelling treatment). To carry outthis gelling, in a treatment chamber 37 filled by ethylene glycol vapor,the wafer W is heated to approximately 100° C. by a heating plate (FIG.2C). In this step, instead of heating, in the treatment chamber 37filled by an ammonia gas, treatment is carried out at the normaltemperature, thereby gelling of the colloids of TEOS may be enhanced bythe ammonia gas which is a basic catalyst. Incidentally, the reason whythe inside of the treatment chamber 37 is filled by the ethylene glycolvapor is to suppress vaporization of the solvent in the coating liquid.

Subsequently, at the solvent replacement unit 4, on the approximaterotation center of the surface of the coated film M on the wafer W,ethanol, HMDS (hexamethyl disilane) and heptane are dispensed in turn,thereby the solvents in the coated film M are replaced by other solvents(solvent replacement treatment). For this, at the solvent replacementunit 4, as shown in FIG. 2D, the wafer W is held in level by an waferholder 21 constituted to be capable of rotating around a vertical axis.In this state, first, ethanol is dripped on the approximate rotationcenter of the surface of the wafer W, thereafter the wafer W is rotatedto make diffuse ethanol on the whole surface of the wafer due tocentrifugal force. Thereby, ethanol dissolves into moisture in thecoated film M, resulting in replacement of the moisture by ethanol.

Subsequently, in the similar manner, by dispensing HMDS on the surfaceof the wafer W, OH groups in the coated film are removed. Then, bydispensing heptane on the surface of the wafer W, the solvent in thecoated film is replaced by heptane. The reason why heptane is employedis that, due to use of a solvent of smaller surface tension, the forceput on the porous structure, that is, a reticular structure of TEOS, isreduced, thereby the reticular structure of TEOS is prevented fromcollapsing.

The wafer W thus carried out the predetermined treatment at the solventreplacement unit 4 is transferred to a bake unit by the main arm 13. Thewafer W is bake treated at this unit, thereby an interlayer insulatingfilm consisting of a silicon oxide film is formed on the surface of thewafer W.

The method of forming a film of the fifth invention is characterized information treatment of a film.

In the following, the coating unit 2 where this treatment is carried outwill be described with reference to the side view of the profile of FIG.29. Reference numeral 431 in the figure denotes a chuck for holding anwafer W level (includes approximately level). This chuck 431 isconstituted of a vacuum chuck for instance, the rear side of the wafer Wis sucked and held. On the approximate center of the bottom surface ofthe chuck 431, a rotation axis 433 capable of going up and down androtating by a driving portion 432 is attached. With such a structure,the chuck 431 is capable of going up and down between a deliveringposition of the wafer W above the fixed cup which will be describedlater and a treatment position of the wafer W shown by the solid line inFIG. 29, and is capable of rotating around the vertical axis.

In the circumference of the chuck 431 and the wafer W which arepositioned at the treatment position, a fixed cup 440 is disposed inorder to surround them. On the upper surface of the fixed cup 440, anopening 441 where the wafer W is passable is formed. The opening portion441 is opened and closed by a cover 442 disposed to be capable of goingup and down. Further, on the bottom surface of the fixed cup 440, adraining pipe 443 and an exhaust pipe 444 are connected.

Above the wafer W which is in a treatment position, a coating liquidnozzle 450 is attached to dispense the coating liquid which will bedescribed later on the approximate center of the surface of the wafer W(the surface where a coated film is formed). This coating liquid nozzle450 is attached to a supporting arm 451 such that the tip end thereof isdirected toward the approximate rotation center of the surface of thewafer. The supporting arm 451 is constituted to be capable of moving ina level direction by a driving portion 452. As the result, the coatingliquid nozzle 450 is capable of moving between a dispensing position (aposition shown in FIG. 29) of dispensing a coating liquid on the surfaceof the wafer, and a nozzle cleaning portion 453 disposed outside thewafer W which is in the treatment position. The nozzle cleaning portion453 is a portion which receives the liquid overflowing from the coatingliquid nozzle 450 and is constituted such that, a liquid exhaust path453 b is connected to the bottom surface of a cylindrical liquidreceiver 453 a, for instance.

The coating liquid nozzle 450 is connected to one end side of a solventdispensing pipe 461 for dispensing a coating liquid X to the nozzle 450.The other end side of the coating liquid dispensing pipe 461 isconnected to a mixing portion 462. This coating liquid dispensing pipe461 has a jacketed structure having an internal pipe and an externalpipe for instance. Through the external pipe, temperature controllingliquid is flowed.

To the mixing portion 462, a plurality, for instance, 2, of reservingtanks 463 and 464 for reserving respectively the first liquid and thesecond liquid which are components of the coating liquid X are connectedthrough solvent dispensing pipes 463 a and 463 b having pumps P1 and P2.The respective liquids reserved in these first and second reservingtanks 463, 464 are mixed at the mixing portion 462, and are dispensed tothe coating liquid nozzle 450 through the coating liquid dispensing pipe461.

Here, the coating liquid X will be described. In this coating liquid X,colloids or particles of a metal alkoxide such as TEOS which is astarting substance of a film component are dispersed in a solvent. As asolvent, ethanol solution, ethylene glycol, water and a trace ofhydrochloric acid (HCl) can be employed.

In such a coating liquid X, the colloids or particles of TEOS areinsoluble or difficult to be dissolved in water. The liquid in which thecolloids or particles of the TEOS, ethylene glycol, water andhydrochloric acid are mixed is reserved in the first reserving tank 463as the first liquid S1. Further, an ethanol solution is an organicsolvent which dissolves water and the colloids and the like of TEOS, andis reserved in the second reserving tank 464 as the second liquid S2.

Next, the formation treatment of a film which is carried out at thecoating unit 2 will be described with reference to FIG. 30A through FIG.30D. First, a cover 442 is elevated up to the position shown by thedotted line in FIG. 29. At the same time, a chuck 431 is elevated up tothe position above the fixed cup 440. In this state, at the position ofthe dotted line in FIG. 29, the wafer W transferred to the unit 3 by themain arm 13 is delivered onto the chuck 431. Then, the chuck 431 islowered to the treatment position, and the cover 442 is lowered to sealthe fixed cup 440.

And, first, as shown in FIG. 30A, the coating liquid X is dispensed onthe approximate rotation center on the surface of the wafer W from thecoating liquid nozzle 450 to form a coated film on the surface. That is,the coating liquid X (mixed liquid) is made by mixing the first liquidS1 and the second liquid S2 at the mixing portion 462, then this coatingliquid X is dispensed on the surface of the wafer W within 6 min. aftermixing of the respective liquids to coat.

In specific, by operating pumps P1 and P2, the predetermined amounts ofthe first liquid S1 and the second liquid S2 are dispensed to the mixingportion 462 from the first reserving and the second reserving tanks 463and 464. At the mixing portion 462, these first and the second liquidsS1 and S2 are mixed to prepare the coating liquid X, then the coatingliquid X is dispensed on the surface of the wafer W through the coatingliquid dispensing pipe 461. Then, by rotating the wafer W, the coatingliquid X is diffused and spread over the whole surface of the wafer dueto centrifugal force to form a coated film. Thus, by dispensing thecoating liquid X on the surface of the wafers W within 6 min. after thefirst and the second liquids S1 and S2 are mixed, the predeterminednumber of the wafers W undergoes film formation.

Incidentally, after films are formed, a thinner is sprayed on the brimportion of the wafer W from a thinner nozzle in the fixed cup 440 notshown in the figure to remove the coated film of the brim portion.Thereafter, the cover 442 and the chuck 431 are elevated to deliver thewafer W from the chuck 431 to the carrying arm 13, then it is carried tothe aging unit 3 and the solvent replacement unit 4 in turn.

Subsequently, at the coating unit 2, before coating the coating liquid Xon the surface of the following wafer W, as shown in FIG. 30B, theinside of the path of the coating liquid X composed of the mixingportion 462 and the coating liquid pipe 461 is cleaned by an organicsolvent. That is, after the coating liquid nozzle 450 is moved above thenozzle cleaning portion 453, supply of the first liquid to the mixingportion 462 is stopped. Then, only the second liquid is dispensed to thecoating liquid dispensing pipe 461 through the mixing portion 462.

By carrying out like this, the flow path of the coating liquid X isreplaced gradually from the upstream side by an organic solvent, theethanol solution S2 in this example (FIG. 30B), before long, iscompletely replaced by the ethanol solution S2 (FIG. 30C). Thereby, theinside of the flow path is cleaned by the ethanol solution S2. In thistime, the coating liquid X and the ethanol solution S2 flowing out ofthe coating liquid nozzle 450 are exhausted from the liquid exhaust path453 b through the liquid receiver 453 a. Here, as an organic solvent forcleaning the flow path, it is preferable to employ a component whichdissolves the starting substance of the film component and water. Assuch organic solvents, alcohol such as an ethanol solution, IPA(isopropyl alcohol) or the like can be employed.

After thus replacing the inside of the flow path by the ethanol solutionS2, as shown in FIG. 30C and FIG. 30D, the first and the second liquidsS1 and S2 are dispensed into the inside of the flow path. Thus, byreplacing the inside of the flow path by the coating liquid X, then, bymoving the coating liquid nozzle 450 to the dispensing position, thewafer W is again subjected to the formation treatment of the coatedfilm. This time, after the coating liquid nozzle 450 is moved to thedispensing position, the inside of the flow path may be replaced by thecoating liquid X, or, on the surface of the wafer W, the ethanolsolution and the coating liquid X may be replaced.

According to the aforementioned example 7, since the coating liquid X ofwithin the film quality deteriorating time period after completion ofmixing of the first and the second liquids S1, S2, for instance, within6 min. after completion of mixing is coated on the surface of the waferW, as obvious from the experimental results which will be describedlater, deterioration of the film quality of coated film can besuppressed.

Here, the experiments which the inventors carried out are as follows.That is, the aforementioned first liquid S1 and the second liquid S2 aremixed to form the coating liquid X. Then, by varying the time periods upto dispensing the coating liquid X on the surface of the wafers W aftermixing, the coated films are formed on the surfaces of the wafers W bythe aforementioned method. Then, the state of such formed coated filmsare observed by visual observation.

This time, the inventors had grasped from experience that the filmquality of the films to be formed deteriorated when the time period upto dispensing on the surface of the wafer W passed approximately 6 min.after the first liquid S1 and the second liquid S2 are mixed. Therefore,in order to confirm the critical point, the experiment was carried outby varying the time periods up to dispensing on the surface of thewafers W such as 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 10 min, and30 min, respectively after mixing.

As to the coated films obtained under the respective conditions, thein-plane uniformity of the film thickness=(standard deviation of filmthickness in the wafer plane)/(average film thickness in the waferplane)×100(%) is obtained. On the other hand, the obtained coated filmsare checked by visual observation. The results are shown in FIG. 31.Here, ∘ denotes a state where no irregularity is observed in the coatedfilm, and × denotes a state where a radial truck is seen on the surfacelike a running truck of a particle. From these results, it is confirmedthat, by employing the coating liquid X of within 6 min after the firstand the second liquids S1 and S2 are mixed, deterioration of the filmquality and in-plane non-uniformity of the film thickness of the formedfilm can be suppressed.

Thus, when the coating liquid X which elapsed more than 5 min. aftermixing of the TEOS and the solvent such as ethanol solution or the likeis employed, fluctuation of the film thickness or film quality of thecoated film occurs, though the mechanism being not clarified, theinventors assume as follows. That is, the coating liquid X is a mixtureof the TEOS and the solvent. When the TEOS and the solvent are mixed,hydrolysis and polymerization of the TEOS occur. When a certain timeperiod elapsed after mixing, the colloids grow too much and deviate fromthe appropriate colloidal state to obtain the best film quality. As theresult, fluctuation in the thickness or the film quality of the coatedfilm are considered to occur.

Here, whereas TEOS is difficult to dissolve in water but it is solublein alcohol, accordingly the hydrolysis or the polymerization of TEOS isconstrued to occur after elapse of a certain time period afterdissolution of the TEOS, water and hydrochloric acid into the ethanolsolution. It is considered that it occurs when the time period of morethan 6 min. had elapsed after the ethanol solution and the othercomponents were mixed, for instance.

Therefore, like example 7, by separating the components of the coatingliquid X into an ethanol solution (the second liquid) and the othercomponents (the first liquid), and by forming the film while employingthe coating liquid X of within 6 min. after mixing of these, the coatingliquid X can be employed before the colloids grow too much. As theresult, it is considered that deterioration of the film quality of thecoated film can be suppressed.

Further, as in example 7, after forming films on the predeterminedpieces of wafers W with a coating liquid X of within 5 min. after mixingof the first and the second liquids S1, S2, before coating the coatingliquid X on the next wafer W, the mixing portion 462 and the flow pathof the down stream side of the mixing portion 462 are cleaned. Thereby,in the flow path, there does not remain the old coating liquid whichelapsed more than 5 min. after mixing. Therefore, when the subsequentwafer W is processed, there is no chance of the old coating liquid Xbeing dispensed on the wafer W, accordingly the film quality of thecoated film is prevented from deteriorating.

Further, if alcohol such as an ethanol solution or the like is employedas the organic solvent in this case, as mentioned above, TEOS, water,and hydrochloric acid dissolve in the ethanol solution. Therefore, sincethe respective components of the coating liquid X existing in the flowpath are dissolved in the ethanol solution, cleaning of the flow pathcan be readily carried out. Further, like example 7, by transferring thefirst and the second liquids S1, S2 respectively from the separatereserving tanks 463, 464 into the mixing portion 462 by pumps P1, P2,the mixing ratio of the first and the second liquids S1, S2 can beadvantageously varied with ease.

Thus, according to the example 7, since the hydrolysis andpolymerization of the coating liquid X dispensed on the surface of thewafer W can be suppressed, deterioration of the film quality of thecoated film due to decomposition of the coating liquid X can besuppressed. As the result, excellent thin films such as interlayerinsulating films can be formed.

In the above described example 7, instead of disposition of the firstand the second reserving tanks 463, 464 or the mixing portion 462, onanother place the first and the second liquids S1, S2 are mixed. Then,within 6 min. after the preparation of the mixed liquid (coating liquidX), the coating liquid may be coated on the surface of the wafer W.Further, vapor of ethylene glycol is dispensed inside the fixed cup 440,after the inside of the cup 440 is filled by the vapor, the coatingliquid X may be dispensed. In this case, there is an effect thatvaporization of the solvent of the coating liquid X can be suppressed.

In the aforementioned method of forming films of the fifth invention,the replacement treatment of the aforementioned solvent is notnecessarily required. That is, by carrying out gelling treatment afterformation of a coated film, a thin film such as an interlayer insulatingfilm may be formed.

According to the fifth invention, the first liquid containing particlesor colloids of a starting material of a film component and water and thesecond liquid consisting of an organic solvent capable of dissolvingwater and the film component are mixed, the mixture of the liquids iscoated on the surface of the substrate within 6 min. after preparationto form a coated film. Thereby, deterioration of the film quality can besuppressed. As the result, an excellent thin film such as an interlayerinsulating film can be obtained.

Incidentally, in the example 7, based on empirical facts or experiments,the film quality deterioration time period is set at 6 min., however,the film quality deterioration time period varies depending on chemicalsor solvents to be employed, treatment conditions or the like.

Therefore, in the case of the conditions being different from theexample 7, the appropriate value of the film quality deterioration timeperiod is determined each time by experiment or the like. Thus,corresponding to the respective conditions, the film qualitydeterioration time periods are determined. Therefore, in the fifthinvention, the film quality deterioration time period is not restrictedto 6 min.

EXAMPLE 8

Next, example 8 involving the sixth invention of the present applicationwill be described.

FIG. 1 is a plan view showing an apparatus involving Example 8.

FIG. 2A through FIG. 2D are diagrams showing schematically therespective steps of a method of forming a film involving example 8.

In FIG. 2A through FIG. 2D, the flow of treatment of forming a film isschematically shown in order. An wafer W prior to the treatment andtaken out by a main arm 13 from the inside of a cassette C of a cassettestage CS is accommodated in a coating unit 2. Then, in a state where theinside of the coating unit 2 is filled by a vapor of solvent, a coatingliquid T is dripped on the surface of the wafer W (cf. FIG. 2A). Thecoating liquid employed here is one in which colloids or particles ofTEOS which is a metal alkoxide are dispersed in a solvent containingorganic solvents such as ethylene glycol and ethyl alcohol and furthercontaining water and a trace of hydrochloric acid. Because of low vaporpressure of ethylene glycol, it remains in the film as the solvent evenafter vaporization of ethyl alcohol, to work for suppressing shrinkageof the film.

Subsequently, when the wafer W is rotated with high speed in a statewhere the inside of the coating unit 2 is filled by the vapor of thesolvent, the coating liquid in which sol of TEOS is dispersed in thesolvent is spread over the surface of the wafer W to form a film F (FIG.2B).

Next, the wafer W is placed on the stage 31 of the aging unit 3 and issealed by the cover 33. Then, under normal temperature, into the agingunit 3, a treatment gas for enhancing gelling of the coated film isintroduced to gel the film (FIG. 2C). The treatment gas is an ammoniagas including water vapor.

Subsequently, in the solvent replacement unit 4, with ethyl alcohol,HMDS (hexamethyl disilane) and heptane, solvent replacement of thegelled film is carried out (FIG. 2D). Thereby, moisture in the coatedfilm is replaced by ethyl alcohol. Further, OH groups in the coated filmare removed by HMDS. Further, the solvent in the coated film is replacedby heptane. Incidentally, the reason why heptane is employed is toprevent the reticular structure of TEOS from collapsing by decreasingthe force put on the porous structure, that is, the reticular structureof TEOS through employment of solvent of small surface tension.Thereafter, the wafer W is treated at the bake unit for 1 min., forinstance. Thus, on the surface of the wafer W, an interlayer insulatingfilm consisting of a silicon oxide film is formed.

FIG. 32 is a diagram diagrammatically showing one example of theaforementioned aging unit 3. As shown in FIG. 32, this aging unit 3comprises a stage 561 thereon the wafer W is placed, a cover 563 sealingthe space above the stage 561 together with it, and an exhaust path 565having an opening in the center portion of the cover 563.

The cover 563 is intimately connected to the circumference portion ofthe stage 561 through a sealing member 562, and constitutes thetreatment chamber 560 together with the stage 561.

And, along the outside of the brim of the wafer W placed on the stage561, a plurality of or slit like gas intakes 564 are opened. Further, onthe bottom surface of the aging unit 3, 3 pieces, for instance, of pins567 capable of going up and down are disposed to be capable of freelyappearing and disappearing. These pins 567 capable of going up and downare driven up and down between the stage 561 and the above positionthereof by a driving source 566 for going up and down the wafer W.

The gas intake 564 a is connected to a treatment gas dispensing pipe581. This dispensing pipe 581 is branched at the midway, the branchedpipes are connected to the first gas generating source 571 and thesecond gas generating source 572 through switching valves V1 and V2,respectively. The first gas generating source 571 and the second gasgenerating source 572 are constituted in the identical manner.

These first gas generating source 571 and second gas generating source572 comprise a tank 574 a reserving commercial ammonia water (NH₄OH)(ammonia concentration: 30% by weight at normal temperature) 573, abubbling gas feeding pipe 575 for carrying out bubbling by introducingan ammonia gas into the ammonia water 573 in the tank 574 b, an exhausttakeout 576 exhausting the treatment gas generated by bubbling, and ameans 577 for maintaining the temperature of the ammonia water 573 at aconstant temperature for instance at the normal temperature.

The means for keeping a constant temperature is not restricted inparticular. As shown schematically in FIG. 32, for instance, the tank574 can be constituted by winding spiral a pipe 578 which is acirculating path of water. In this case, the pipe 578 is connected to acirculating device of water not shown in the figure and water adjustedto the normal temperature is flowed all the time. Thereby, thetemperature of the ammonia water 573 reserved in the tank 574 is alwaysmaintained at the normal temperature.

The treatment gas feeding pipe 581 is branched, between the first gasgenerating source 571 and the valve V1, and between the second gasgenerating source 572 and the valve V2, respectively, into bypasses 582,583 proceeding to the exhaust paths through switching valves V3, V4.

Next, operation of the aging unit 6 of the aforementioned configurationwill be described. The ammonia water in the first and the second gasgenerating sources 571, 572 is maintained at the normal temperature inadvance by circulating the temperature controlled water. Now, in thefirst gas generating source 571, bubbling of ammonia gas is beingcarried out and the ammonia gas 573 of the first gas generating source571 has already reached the saturated concentration of ammonia(approximately 33% by weight). Thereby, the treatment gas consisting ofammonia gas containing water vapor (considered to be in a nearlysaturated state) is generated and is exhausted through valve V3. Duringthis, the switching valve V2 on the second gas generating source 572side is closed.

Then, the wafer W is carried into the treatment chamber 560 from thecoating unit 2, thereafter treatment is carried out for thepredetermined time period. During the treatment, the switching valve V1on the first gas generating source 571 side is opened, and the valve V3to the exhaust side is closed, and the treatment gas is dispensed fromthe first gas generating source 571 to the inside of the treatmentchamber 560 (the first treatment step).

In the case of the ammonia water in the first gas generating source 571decreasing and the ammonia water being replenished thereto, by lettingstart bubbling of the ammonia gas in advance at a predetermined timingeven at the second gas generating source 572, the ammonia water 573 ismade to reach the saturated concentration of ammonia and to generateammonia gas containing water vapor. During this, on the second gasgenerating source side 572, the switching valve V2 is kept closed, andby opening the valve V4 to the exhaust side, the generated gas isreleased directly to the exhaust path through the bypass 583 from thesecond gas generating source 572 (preparatory exhaust step).

In this state, the valve V1 which is on the first gas generating source571 side and was being opened is closed to stop feeding of the treatmentgas to the treatment chamber 560 from the first gas generating source571. At the same time, the valve V2 which is on the second gasgenerating source 572 side and was being closed is opened to feed thetreatment gas to the treatment chamber 560 from the second gasgenerating source 572. In this time, at the same time with switching ofvalves V1, V2, the valve V3 which is on the first gas generating source571 side and was being closed is opened. Thereby, the gas generated atthe first gas generating source 571 is made to be released to theexhaust path. At the same time with this, the valve V4 which is on thesecond gas generating source 572 side and was being opened is closed(the second treatment step).

Thereafter, the ammonia water is replenished to the first gas generatingsource 571 to let generate the ammonia gas containing water vapor fromthe ammonia water which reached the saturated concentration of ammoniaby bubbling of ammonia gas. On the other hand, in the case of theammonia water in the second gas generating source 572 decreasing and theammonia water being replenished thereto, by letting bubbling going on atthe first gas generating source 571, similarly the treatment gas feederis again switched from the second gas generating source 572 to the firstgas generating source 571.

Here, the timing of starting bubbling at the second gas generatingsource 572 during replenishment of the ammonia water to the first gasgenerating source 571 is such a timing at which, when the ammonia wateris replenished to the first gas generating source 572, a state, wherethe ammonia gas containing water vapor is generated at the second gasgenerating source 572, is attained. Such a timing or the timing when theammonia water at the first and the second gas generating sources 571,572 is replenished may be determined by an operator. Or, by disposingwater level sensors to the respective gas generating sources 571, 572,thereby the water level of the ammonia water may be automaticallydetected, to determine the appropriate timing.

Further, the switching valves V1, V2, V3, and V4 may be designed to bemanually switched by an operator. Or, a controller for controllingswitching of these may be disposed to switch automatically according tothe predetermined timings.

FIG. 33 is a diagram showing diagrammatically one example of a gas flowpath in the aging unit 3 of configuration shown in FIG. 32. In thisexample, ammonia gas is fed to the first and the second gas generatingsources from a common gas feeding source 570. And as shown in FIG. 33,between the valve V1 and the branching point of the treatment gasfeeding pipe 581, a conductance control portion P1 is disposed. Thisconductance control portion P1 is disposed so as to match theconductance from the first gas generating source 571 to the treatmentchamber 560 to the conductance from the second gas generating source 572to the treatment chamber 560. This conductance control portion P1 isprovided with a structure by which the cross section of the gas flowpath, that is, resistance of gas flow can be controlled. Specificcontrol of the conductance is carried out such that, by use of a flowmeter 580 disposed at the gas feeding pipe 581, the flow rate when thegas is flowed from the first gas generating source 571 and that when thegas is flowed from the second gas generating source are made equal.Incidentally, the conductance control portion P1 may be disposed,instead of at the aforementioned position, at positions between from thevalve V2 to the aforementioned branching point, or may be disposed onboth positions.

In addition, even on the first bypass (the first exhaust path) 582reaching directly to the exhaust path 565 from the first gas generatingsource 571 without through the treatment chamber 560 but through thevalve V3, a conductance controlling portion P2 is disposed. Theconductance of this conductance controlling portion P2 is set theconductance of the whole gas flow path from the first gas generatingsource 571 through the valve V3 on the exhaust side, the conductancecontrolling portion P2, and the first bypass 582 to the exhaust path565, to be equal with the conductance of the whole gas flow path fromthe first gas generating source 571 through the valve V1 on thetreatment chamber side and the treatment chamber 560 to the exhaust path565.

Further, even on the second bypass (the second exhaust path) 583 fromthe second gas generating source 572 without through the treatmentchamber 560 but through the valve V4 directly to the exhaust path 565,the conductance controlling portion P3 is disposed. The conductance ofthis conductance controlling portion P3 is set the conductance of thewhole gas flow path from the second gas generating source 572 throughthe valve V4 on the exhaust side, and the second bypass 583 to theexhaust path 565 to be equal with that of the whole gas flow path fromthe second gas generating source through the valve V2 on the treatmentchamber 560 side and the treatment chamber 560 to the exhaust path 565.

By controlling the conductance of the gas flow path like this, when,while letting gas flow from the first gas generating source 571 to thebypass 582 for instance, an wafer is introduced into the treatmentchamber 560 and the gas flow path is switched to the treatment chamber560 side, or when the feeding source of the treatment gas to thetreatment chamber 560 is switched between the first gas generatingsource 571 and the second gas generating source 572, the fluctuation ofthe flow rate of the treatment gas and the pressure inside the treatmentchamber 560 can be suppressed. For instance, provided that the first gasgenerating source 571 is switched to the second gas generating source572, the gas flow from the first gas generating source 571 to thetreatment chamber 560 is stopped, and at the same time, the gas flowfrom the second gas generating source 572 to the bypass 583 is switchedto the valve V2 side. In this case, as mentioned above, since theconductances of the respective flow paths were made equal, the pressureand flow rate of the gas flowing into the treatment chamber 560, thoughbeing varied a little due to switching of the valve, hardly showfluctuation. This situation is identical when the source of thetreatment gas is returned from the second gas generating source 572 tothe first gas generating source 571.

According to the aforementioned example 8, simultaneously with the firsttreatment step where an wafer W is treated by feeding an ammonia gascontaining water vapor from the first gas generating source 571 to theinside of the treatment chamber 560, even at the second gas generatingsource 572, by letting the ammonia gas containing water vapor generate,preparatory exhaust step of releasing the ammonia gas containing watervapor directly to the exhaust path 565 through the bypass 583 is carriedout, and when the ammonia water is replenished to the first gasgenerating source 571, the feeding source of the treatment gas to thetreatment chamber 560 is switched from the first gas generating source571 to the second gas generating source 572, thereby the secondtreatment step of treating the wafer W is carried out, accordingly uponreplenishing the ammonia water feeding of the treatment gas is notinterrupted.

Further, according to the aforementioned example 8, since the ammoniawater 573 in the first and the second gas generating sources 571, 572 isalways being held at the normal temperature by the temperaturecontrolling water, the temperature fluctuation due to vaporization andabsorption of ammonia can be suppressed, thereby fluctuation of watervapor is suppressed, resulting in stabilization of the process. In thecase of ammonia water particularly, since a slight temperature variationinduces a large variation of the saturated concentration, the generatingamount of the gas is considered to fluctuate due to the externaltemperature disturbance. However, according to example 8, the flow rateof the ammonia gas can be stabilized.

Further, upon introducing the ammonia gas after carrying in an wafer Winto the treatment chamber 560, since the conductance of the each gasflow path of the bypass 582 side and the treatment chamber 560 side isequal each other, upon switching the valves V1 and V3, the ammonia gasis introduced from the beginning with the predetermined pressure andflow rate. Further, even when the first gas generating source and thesecond gas generating source 571, 572 are switched, the pressure and theflow rate of the ammonia gas do hardly fluctuate, accordingly thegelling treatment can be carried out with stability. As the result, thefilm thickness and film quality of the coated films can be suppressedfrom fluctuating, uniform treatment between the wafers can be carriedout. Further, since the ammonia water can be replenished withoutinterrupting operation each time, thereby lowering of throughput can beprevented from occurring.

In the aforementioned sixth invention, various variations can beapplicable. The temperature control means 577, for instance, canmaintain the ammonia water 573 in the tank 574 at the normal temperatureby winding the tank 574 of the first gas generating source 571 and thesecond gas generating source 572 by a heater of resistance heating orthe like, or by employing an immersion heater. Further, the valves V1and V2 can be substituted by a single 3-way valve.

Further, the sixth invention, as shown in FIG. 34, can be aconfiguration in which a single gas generating source 579 generating anammonia gas saturated by water vapor is connected to the treatmentchamber 560. The gas generating source 579 can be constituted asidentical as the first gas generating source 571 or the second gasgenerating source 572 shown in FIG. 33. In this example, a switchingvalve VS is disposed at the midway of the treatment gas feeding pipe 581which communicates and connects the gas generating source 579 and thetreatment chamber 560. And, a bypass 584 is disposed branched betweenthe valve VS and the gas generating source 579. This bypass 584 iscommunicated and connected to the exhaust path 565 through the switchingvalve V6 and the conductance control portion P4. By conductance controlportion P4, the conductance of the flow path through the treatmentchamber 560 and that of the flow path through the bypass 584 are madeequal.

According to the example shown in FIG. 34, after replenishment of theammonia water, the preparatory exhaust step of releasing directly to theexhaust path 565 through the bypass 584 is carried out until theconcentration of the ammonia water is stabilized at the predeterminedconcentration, and when subsequently the flow path is switched to thetreatment chamber 560 side, since the conductance of the flow pathbefore and after switching are equal, the ammonia gas can be fed withthe predetermined flow rate into the treatment chamber 560 from thebeginning, therefore, the stable gelling treatment can be carried out.In order to carry out treatment step of treating the wafer W by feedingthe ammonia gas saturated by water vapor into the treatment chamber 560by switching the valve V5 and the valve V6 to open state and closedstate, respectively, with stability, the ammonia gas containing watervapor can be always introduced into the treatment chamber 560. Further,since, through the temperature control of the ammonia water of the gasgenerating source 579 and the conductance control of the gas flow path,the treatment temperature, the flow rate of the treatment gas and thepressure in the treatment chamber 560 can be held at the constantvalues, uniform treatment can be carried out between the wafers, therebythe fluctuation of the film quality between the wafers can besuppressed.

Incidentally, the subject to be treated is not restricted to the wafer,but can be a glass substrate for liquid display device. Further, thesixth invention is not restricted to the case of gelling by use of theammonia gas. It can be applied to a device in which, for instance, whileexhausting the treatment gas from the bypass, the subject to be treatedis carried into the treatment chamber, thereafter by switching the flowpath from the bypass to the treatment chamber side, the treatment gas isintroduced.

Further, in the aforementioned example 8, by disposing 2 tanks 574 ofammonia, the ammonia gas generated therefrom is switched in turn, but 3and more of tanks 574 can be disposed. In that case, while shifting thetimings generating ammonia from the respective tanks 574, by switching 3tanks 574 and the feeding pipe 581 in turn, the ammonia gas can beflowed always at a constant flow rate.

As shown in the above, according to the sixth invention, in the case oftreatment being carried out by introducing the treatment gas into thetreatment chamber, the stable treatment can be carried out.

EXAMPLE 9

Next, example 9 involving the seventh invention of the presentapplication will be described.

FIG. 36 is a plan view showing diagrammatically the whole configurationof the apparatus of forming a film of example 7 involving the seventhinvention of the present application.

In the figure, reference numeral 611 denotes an input/output port ofwafers W which are substrates, reference numeral 612 denotes a carryingarm constituting a receiving portion, and reference numeral 613 denotesa main arm constituting a main carrying portion. On one side of acarrying way (guide rail) 614 of the main arm 613, a coating/aging unit620 provided with a coating unit 620 which is a coating portion and anaging unit 630 which is a gelling treatment portion, and a solventreplacement unit 640 which is a solvent replacement portion are arrangedin this order.

Further, also on the other side of the carrying way 614, the treatmentunits U1 through U4 are arranged.

To these treatment units U1 through U4, the units for carrying outhydrophobic treatment, cooling treatment and heat treatment (baketreatment) are respectively assigned. In this example 9, the unit forcarrying out the hydrophobic treatment and the cooling treatmentcorresponds to the pretreatment portion for carrying out the treatmentpreceding the coating of the coating liquid on the wafer W. Further, theunit for carrying out the heat treatment corresponds to the heatingportion for drying the wafer W treated at the aging unit 630.

The carrying arm 612 and the main arm 613 are constituted to be capableof moving freely in the X direction and in the Y direction, and to becapable of rotating freely. An wafer W is taken out of a cassette Cdisposed on a cassette stage CS by the carrying arm 612 and is deliveredto the main arm 613. Further, the wafer W is sequentially carried by themain arm 613 to the respective units 620, 640, and U1 through U4.

Subsequently, the coating/aging unit 620 will be described withreference to FIG. 37 through FIG. 39. To this coating/aging unit 620, asshown in FIG. 37, a coating unit 620 and an aging unit 630, forinstance, are disposed adjacent thereto.

First, the coating unit 620 will be described with reference to FIG. 38.The coating unit 620 comprises a fixed cup 622 for accommodating anwafer W, a cover 621 opening and closing an upper opening thereof, avacuum chuck 625 disposed to be capable of rotating in the fixed cup622, and a coating liquid nozzle 626 for dispensing the coating liquidon the wafer W held on the vacuum chuck 625.

At the bottom portion of the fixed cup 622, a breakthrough is opened,therethrough a rotation axis 624 is inserted. The upper end of thisrotation axis 624 is combined with the vacuum chuck 625, the lower endof the other rotation axis 624 is combined to a driving portion 623disposed below the lower side of the fixed cup 622. Through thisrotation axis 624, driving force of rotation is transmitted from thedriving portion 623 to the vacuum chuck 625. Further, the rotation axis624 is capable of going up and down in the up/down direction. Thecoating liquid nozzle 626 is disposed combined with the cover 621 andthe coating liquid is dispensed on the central portion of the wafer W.

To the cup 622, a solvent vapor feeding pipe 627 for feeding the vaporof the solvent which is sent from the solvent vapor generating source627 a and is employed in the coating liquid is connected. To the cup622, a drain pipe 628 and an exhaust pipe 629 are further connected.

Next, the aging unit 630 will be described with reference to FIG. 39.This aging unit 630 comprises a heating plate 631 consisting of ceramic,for instance, including a heater 631 a, and a cover 633 disposedadjacent to the upper side of the heating plate 631 so as to form aspace S, which constitutes a treatment chamber there, by partitioningthe upper space of the heating plate 631.

The cover 633 is, in addition to being intimately connected to the brimportion of the heating plate 631 through a sealing member 632, free incontacting and detaching with respect to the heating plate 631.

On the upper surface of the heating plate 631, a groove like gas supplyis formed such that surrounds the exterior circumference of the wafer Wto be placed on the heating plate 631, the bottom portion of this gassupply is connected to the gas feeding path 634.

On the central portion of the cover 633, an intake for inhaling a gas isformed, and this intake is connected to an exhaust path 635communicating with the exterior.

The bottom portion of the heating plate 631, 3 pieces of pins 636 forgoing up and down disposed to be capable of appearing and disappearingfreely are provided. These pins 636 for going up and down goes up anddown the wafer W between the heating plate 631 and the above positionthereof. Incidentally, a heating means such as a heater is preferablydisposed even to the cover 633.

These fixed cup 622 and aging unit 630 of the coating unit 620, as shownin FIG. 37, are disposed adjacent each other on a common level basestage 650. And, between these units 620 and 630 on the base stage 650, asub-arm mechanism constituting an auxiliary carrying portion isdisposed.

This sub-arm mechanism 5 is exclusively used for carrying the wafer Wtreated at the coating unit 620 to the aging unit 630. For this,together with disposition of, for instance, a sub-arm 651 for holding apart of the circumference portion of the bottom surface of the wafer W,this sub-arm 651 is constituted to be capable of moving in the leveldirection (the X direction in FIG. 1) along a guide rail 652, inaddition, the guide rail 652 itself is constituted to be capable ofrotating in the level direction through a vertical rotation axis 654 bya driving portion 653. Thus, the sub-arm 651 is capable of reversing thedirection between the coating unit 620 and the aging unit 630 forreceiving the wafer W. At the same time, the sub-arm is capable ofmoving between an waiting position (the position shown by the solid linein FIG. 37) and a position receiving the wafer W from the coating unit620, and between the waiting position and a position delivering thewafer W to the aging unit 630. Further, in this example, the guide rail652 is disposed at the above side than the base stage 650.

Further, above the sub-arm 651, above the guide rail 652 of the carryingpath of the wafer W between the coating unit 620 and the aging unit 630,a solvent vapor feeding portion 655 which is a means for feeding vaporof the solvent component which is employed in the coating liquid isdisposed. This solvent vapor feeding portion 655 comprises a dispersingroom 656 for dispersing the solvent vapor and a vapor diffusing plate657. The dispersing room 656 is disposed so as to opposes the sub-arm651 in the waiting position, and the diffusing plate 657 is attached tothe bottom surface of the dispersing room 656 and has a structure inwhich a plurality of steam holes 657 a are bored. To the dispersing room656, a solvent vapor feeding pipe 658, for instance, for feeding thesolvent vapor generated at a solvent vapor generating source, which isnot shown in the figure, is connected.

Subsequently, the solvent replacement unit 640 will be described withreference to FIG. 40.

This unit 640 comprises a vacuum chuck 641 rotating the wafer W whileholding it in level, a rotary cup 642 which is disposed to surround thewafer W on this chuck 641 and has a hole 640 for exhausting liquid, afixed cup 643 which is disposed outside the rotary cup 642 and in whichan waste liquid path 641 a and an waste gas path 641 b are connected,and a nozzle 644 for dispensing the solvent to the wafer W. Further,reference numeral 645 in the figure denotes a driving portion forrotating and going up and down the rotation axis 641 a of the chuck 641,and reference numeral 642 a denotes a driving portion for rotating therotary cup 640.

The opening on the upper surface of the fixed cup 643 is opened andclosed by a cover 646 capable of going up and down. Further, as thenozzle 644 in this example, 3 pieces of nozzles 644 a, 644 b, and 644 cfor ejecting ethanol, HMDS (hexamethyl disilane) and heptane,respectively, are prepared. These nozzles 644 a, 644 b, and 644 c aregrasped and taken out of the nozzle receiving portions 648 a, 648 b, and648 c, respectively, and are transferred to the above of the centralportion of the wafer W.

In this apparatus of forming a film, the wafer W undergone thehydrophobic treatment and the cooling treatment is carried in turn tothe coating/aging unit 620, the solvent replacement unit 640, and theunit for carrying out bake treatment, and by carrying out thepredetermined treatment at the respective units, an interlayerinsulating film consisting of a silicon oxide film is formed on thesurface of the wafer W.

Subsequently, the treatments carried out at the coating/aging unit 620and the solvent replacement unit will be described. First, at thecoating/aging unit 620, the coating liquid is coated on the surface ofthe wafer W at the coating unit 620 to form a coated film. Thereafter,the wafer W is carried to the aging unit 630 by the sub-arm 651. Then,the particles or the colloids of the coated film formed on the wafer Wat the unit 630 are gelled.

In specific, at the coating unit 620, the wafer W carried to the coatingunit 620 by the main arm 613 is delivered to the chuck 625 at theposition of the dotted line in FIG. 38 for instance, after the chuck 625is lowered, the cup 622 is sealed by the cover 621. The coating liquidused here can be prepared by dispersing the colloids or particles ofTEOS which is a metal alkoxide in the solvent which contains organicsolvent such as ethylene glycol and ethyl alcohol, water and a trace ofhydrochloric acid. Ethylene glycol plays, other than the role of, uponcoating, adjusting the viscosity of the coating liquid to an appropriatevalue, another role of suppressing vaporization of ethyl alcohol byremaining there as the solvent because, at the steps after the coatingstep, ethyl alcohol the vapor pressure of which is low vaporizes almostcompletely. This is based on the higher vapor pressure of ethyleneglycol.

And, in this example, while exhausting from the exhaust pipe 629, thevapor of ethylene glycol is fed into the cup 622 from the solvent vaporfeeding pipe 627. The exhausting is ceased after the inside of the cup622 is filled by the vapor of ethylene glycol, and the coating liquid isfed on the central portion of the wafer W from the nozzle 626. Then, thewafer W is rotated by the chuck 625, the coating liquid is spread on thesurface of the wafer W due to centrifugal force to form a film. Thereason why the treatment is carried out in such a state where the insideof the cup 622 is filled by the vapor of ethylene glycol is to suppressthe vaporization of the solvent in the coating liquid. Incidentally,though not shown in the figure, thereafter, the solvent is sprayed onthe circumference portion of the wafer W from the nozzle in the cup 622to remove the coated film of the circumference portion.

After the coating treatment is carried out thus at the coating unit 620,the wafer W is carried to the aging unit 630 by the sub-arm 651. First,in a state where the cover 621 is lifted a little for instance, theinside of the cup 622 is evacuated, after the cover 621 and the chuck625 are raised, the wafer W is delivered from the chuck 625 to thesub-arm 651. That is, the solvent vapor such as that of ethylene glycolis fed on the guide rail 652 from the solvent vapor feeding portion 655,the direction of the sub-arm 651 is turned to the side of the coatingunit 620, the sub-arm 651 is moved from the waiting position to theposition where the wafer W is received from the coating unit 620, andthe wafer W is delivered from the chuck 625 to the sub-arm 651.

Then, the cover 633 of the aging unit 630 is raised, the direction ofthe sub-arm 651 is turned to the side of the aging unit 630, the sub-arm651 is moved to the position where the wafer W is delivered to the agingunit 630, by cooperation of the pins 636 for going up and down and thesub-arm 651, the wafer W is delivered from the sub-arm 651 on theheating plate 631.

Next, at the aging unit 630, the colloids of TEOS contained in thecoated film on the wafer W is gelled, to link the colloids reticular.That is, at the aging unit 630, after the wafer W is placed on theheating plate 631, the cover 633 is closed, while evacuating from theexhaust path 635, the vapor of ethylene glycol for instance isintroduced into the treatment chamber from the gas feeding path 634.Here, the wafer W is heated to the temperature of around 100° C., forinstance.

The treatment of linking the colloids reticular by gelling the colloidsof TEOS is expedited by heating the coated film, however, by employingan ammonia gas instead of heating, the ammonia gas is operated on TEOSas a catalyst, thereby the gelling may be expedited. Further, the reasonwhy the vapor of ethylene glycol is introduced into the treatmentchamber is to suppress the vaporization of the solvent in the coatedfilm, therefore, the piping and the vapor generating source arecontrolled in their temperature such that the vapor is saturated (100%by the relative humidity of ethylene glycol) at the temperature of thetreatment chamber, for instance.

Subsequently, the treatment carried out at the solvent replacement unit640 will be described. The wafer W treated at the aging unit 630 isdelivered from the heating plate 631 to the main arm 613, then istransferred to the solvent replacement unit 640 by this main arm 613.And, at this unit 640, a solvent other than the solvent of the coatingliquid is fed, thereby the solvent in the coated film formed on thewafer W is replaced by the other solvent.

In specific, in a state where the cover 646 is open, at the aboveposition of the fixed cup 643, the wafer W is delivered to the chuck 641from the main arm 613, and the chuck 641 is lowered. Then, first,together with dripping chemicals in which moisture is soluble, forinstance, ethanol on the approximately central portion of the wafer Wfrom the nozzle 644 a, the wafer W and the rotary cup 642 are rotated,thereby ethanol is diffused over the whole surface of the wafer W due tothe centrifugal force. Thereby, ethanol dissolves in the moisture in thecoated film, resulting in replacement of the moisture by ethanol.

Subsequently, the cover 646 is opened, similarly HMDS is dispensed onthe approximate rotation center of the wafer W to remove OH groups inthe coated film. Further, by dispensing heptane on the approximaterotation center of the wafer W, the solvent in the coated film isreplaced by heptane. The reason why heptane is employed here is toprevent the reticular structure of TEOS from collapsing by reducing theforce added on the porous structure, namely, reticular structure of TEOSthrough use of the solvent of low surface tension. Incidentally, theabove example of the solvent replacement unit 640 is described of thejacketed cup structure consisting of the fixed cup 643 and the rotarycup 642, however, as identical as the coating unit 620, a structure withonly a fixed cup may be employed.

In the aforementioned example 9, the coating unit 620 and the aging unit630 are disposed adjacently inside the same unit 620, thereby the waferW is transferred by an exclusive sub-arm 651 from the coating unit 620to the aging unit 630. Therefore, the wafer W on which the coatingtreatment is carried out at the coating unit 620 is transferred withoutdelay to the aging unit 630 without waiting transfer of the wafer W andis treated. Accordingly, since gelling treatment can be carried out in astate where the vaporization of the solvent in the coated film issuppressed, desired film thickness and film quality can be secured.

Further, the distance of the transfer path between the coating unit 620and the aging unit 630 is short, accordingly the transfer time becomesshort. Accordingly, vaporization of the solvent in the coated filmduring transfer can be reduced further more. Further, since the vapor ofethylene glycol is supplied on the transfer path, the vaporization ofthe solvent during transfer is further suppressed by this ethyleneglycol.

When there is no sub-arm 651, transfer between the coating unit 620 andthe aging unit 630 is carried out by the main arm 613. Therefore, evenif the coating treatment is completed, in the case of the main arm 613being employed for transfer between the other units, it is required towait for the main arm 613. Further, since the main arm 613 moves alongthe guide rail 614 in the center, the transfer path between the coatingunit 620 and the aging unit 630 becomes long, resulting in the longertransfer time. Therefore, since it takes a long time to transfer thewafer W from the coating unit 620 to the aging unit 630, the amount ofvaporization of the solvent in the coated film is liable to increase.

Subsequently, modification example of example 9 will be described withreference to FIG. 41 and FIG. 42. This example is characterized in that,together with covering the whole coating and aging unit 620 by thetreatment chamber (case) 660, the inside of the treatment chamber 660 isfilled by the vapor of the solvent component of the coated film such asethylene glycol. On the side wall opposite to the guide rail 614 of thetreatment chamber 660, an opening 661 a for delivering the wafer W fromthe main arm 613 to the coating unit 620, and an opening 661 b fordelivering the wafer W from the aging unit 630 to the main arm 613 arerespectively disposed on the appropriate positions, and these openings661 a, 661 b are always closed by the doors 662 a, 662 b.

Further, to the treatment chamber 660, a solvent vapor feeding pipe 664for feeding the vapor of ethylene glycol generated at the solvent vaporgenerating source 663 and an exhaust pipe 665 are connectedrespectively. In this example, a means for feeding the vapor of thesolvent component into the treatment chamber 660 is constituted of thesolvent vapor generating source 663 and the solvent vapor feeding pipe664.

In this example, while evacuating the inside of the treatment chamber660, by feeding the vapor of ethylene glycol into the treatment chamber660, the inside of the treatment chamber, for instance, is adjusted tobe saturated by the vapor of ethylene glycol. Then, in a state where theinside of the treatment chamber 660 is made the atmosphere of ethyleneglycol, the door 662 a is opened, the wafer W is delivered from the mainarm 613 on the chuck 625 of the coating unit 620, and the door 662 a isclosed. Then, treatment for forming a coated film is carried out asdescribed above, the wafer W is transferred from the coating unit 620 tothe aging unit 630 by the sub-arm 651, and at the aging unit 630 gellingtreatment is carried out. Thereafter, the door 662 b is opened, and thewafer W is delivered from the heating plate 631 to the main arm 613.

In such a configuration, since the treatment chamber is filled by thevapor of ethylene glycol, all over the steps from the execution of thecoating treatment at the coating unit 620 up to the execution of gellingtreatment at the aging unit 630, the vaporization of the solvent in thecoated film can be suppressed. Since the gelling of the coated film isfurther suppressed thereby, the thin film of more excellent quality canbe formed.

Subsequently, still another modification example of example 9 will bedescribed with reference to FIG. 43. In this example, a coating unit 620and an aging unit 630 and a solvent replacement unit 640 are disposedadjacently in the same unit 670 in this order, and, between the agingunit 630 and the solvent replacement unit 640, a sub-arm mechanism 672constituting an auxiliary transfer portion for transferring exclusivelythe wafer W treated at the aging unit 630 to the solvent replacementunit 640 is disposed.

Also in this example, between the coating unit 620 and the aging unit630, a sub-arm mechanism 650 for exclusively transferring the wafer Wtreated at the coating unit 620 to the aging unit 630 is disposed, thesub-arm mechanism 670 between the aging unit 630 and the solventreplacement unit 640 is constituted identically as the sub-arm mechanism650. That is, the sub-arm 671, together with the direction beingreversed between the aging unit 630 and the solvent replacement unit640, is constituted to be capable of moving along the guide rail(transferring path) 672 between the both units 630, 640.

In this example, the wafer W is delivered from the main arm 613 onto thechuck 625 of the coating unit 620, after the coating treatment iscarried out at the coating unit 620, the wafer W is transferred to theaging unit 630 by the sub-arm 651, to deliver to the heating plate 631.Then, after the gelling treatment is carried out at this unit 630, thewafer W is delivered to the sub-arm 671 to transfer to the solventreplacement unit 640, then is delivered to the chuck 641. And, aftersolvent replacement treatment is carried out at this unit 640, the waferW is delivered from the chuck 641 to the main arm 613, and the wafer Wis transferred by the-arm 613 to a unit for carrying out bake treatment.

In such a configuration, not only between the coating unit 620 and theaging unit 630, but also between the aging unit 630 and the solventreplacement unit 640, transfer of the wafer W is carried out withoutdelay. Accordingly, since the gelling treatment can be carried out in astate where vaporization of the solvent in the coated film issuppressed, in addition to suppression of film shrinkage anddeterioration of the film quality, the time period during which thelarge surface tension of the solvent is added on the reticular structureof TEOS is short, accordingly collapse of the film structure issuppressed, resulting in a thin film of further excellent quality.

In the aforementioned seventh invention, the auxiliary transfer portionmay be constituted as shown in FIG. 44. In this example, for instance, acoating unit 620, an aging unit 630, and a solvent replacement unit 640are constituted as different units each other. The auxiliary transferportion 680 is provided with a pair of arm members 681 a, 681 b whichhold the wafer W by nipping a part of both circumference portions of thewafer W for instance, and these arm members 681 a, 681 b are constitutedto be capable of freely opening and closing in the Y direction forinstance by an opening and closing mechanism 682. Further, the openingand closing mechanism 682 is constituted to be movable in the Xdirection along the guide rail 683 at a position above the respectiveunits 620, 630, and 640.

In such a configuration, the wafer W is exclusively transferred alongthe guide rail 683 from the coating unit 620 to the aging unit 630, andfrom the aging unit 630 to the solvent replacement unit 640, held by thearm members 681 a, 681 b.

Therefore, even in the case of these units 620, 630, and 640 beingconstituted as the separate units, the wafer W is transferred withoutdelay between these units, as the result, the vaporization of thesolvent in the coated film can be suppressed, accordingly deteriorationof the film quality of the thin film can be prevented from occurring.

Incidentally, this auxiliary transfer portion can be applied even in thecase of the coating unit 620, the aging unit 630, and the solventreplacement unit 640 being constituted as the same unit, also can beapplied for transfer only between the coating unit 620 and the agingunit 630.

Further, the seventh invention can be applied even in the apparatus offorming a film of vertical type as shown in FIG. 45. The apparatus willbe briefly described with reference to FIG. 45. Reference numeral 691 inthe figure denotes a main arm constituted to be capable of freely goingup and down, freely moving forward and backward, and freely rotating,and, on one side (left side) of the main arm 691, a hydrophobictreatment unit 692 which is a pre-treatment step for carrying out thehydrophobic treatment of the wafer W, and 5 heating units 693 a through693 e, for instance, constituting the heating portion for carrying outheat treatment (bake treatment) to the wafer W are piled up from thebottom in this order.

On the other hand, on the other side (right side) of the main arm 691, areceiving portion 694 for receiving the wafer W from outside theapparatus, a coating unit 620, an aging unit 630, and a solventreplacement unit 640 are piled up from the bottom in this order. Thus,on both sides of the main arm 691, a plurality of unit groups aredisposed respectively, and, between these unit groups, a transfer pathof the main arm 691 is formed. On the side portion of the coating unit620 and the aging unit 630, for instance, the opposite side of thetransfer path of the main arm 691, in a case 695, the sub-arm 696constituting the auxiliary transfer portion is disposed to be capable offreely going up and down, freely moving forward and backward, and freelyrotating, and the inside of the case 695 is a transfer path of thesub-arm 696.

Even in such a configuration, since the wafer W is exclusivelytransferred between the coating unit 620 and the aging unit 630 by thesub-arm 696, transfer between these units 620, 630 is carried outwithout delay. Accordingly, vaporization of the solvent in the coatedfilm can be suppressed and the film quality of the thin film isprevented from deteriorating. Also in this example, the inside of thecase 695 may be made an atmosphere of ethylene glycol, or, by extendingthe case 695 up to the side of the solvent replacement unit 640, thewafer W may be exclusively transferred between the aging unit 630 andthe solvent replacement unit 640 by the sub-arm 696. Incidentally, inthe seventh invention, the substrate is not restricted to the wafer butcan be glass substrate for liquid crystal display.

According to the seventh invention, after the coating liquid in whichcolloids or particles of the starting material of the film component aredispersed in the solvent is coated on the substrate, the subsequent stepcan be carried out without delay, accordingly a thin film of excellentquality such as an interlayer insulating film can be obtained.

What is claimed is:
 1. An aging unit, comprising: a treatment chamberhaving a sealing mechanism, for accommodating a substrate having formedthereon a film containing a solvent and particles or colloids of astarting substance of a film component; a heater for heating thesubstrate; a carrier gas feeding system for feeding the carrier gastoward the treatment chamber; a solvent dispensing system for dispensingthe solvent toward the treatment chamber; a mixing system for forming amixed gas containing a solvent vapor from the carrier gas feeding systemand the solvent dispensing system; and a control mechanism forcontrolling a solvent concentration of the mixed gas, wherein thecontrol mechanism controls the solvent concentration to a first averageconcentration during a predetermined time after the substrate is carriedinto the treatment chamber, and the control mechanism controls thesolvent concentration to a second average concentration higher than thefirst average concentration after the predetermined time has passed. 2.The aging unit as set forth in claim 1, wherein the control mechanismincreases the solvent concentration continuously corresponding to anincrease of a temperature of the substrate after the substrate iscarried into the treatment chamber until the solvent concentrationreaches the second average concentration.
 3. The aging unit as set forthin claim 1, wherein the control mechanism controls a time-averagedsolvent concentration so as to increase the solvent concentrationcontinuously corresponding to an increase of a temperature of thesubstrate after the substrate is carried into the treatment chamberuntil the solvent concentration reaches the second averageconcentration.
 4. An apparatus for forming a film, comprising: a coatingunit for coating, on a surface of a substrate, a coating liquid in whichparticles or colloids of a starting substance of a film component aredispersed in a solvent; an aging unit comprising a treatment chamberhaving a sealing mechanism, for accommodating the substrate havingformed thereon the film, a heater for heating the substrate, a carriergas feeding system for feeding the carrier gas toward the treatmentchamber, a solvent dispensing system for dispensing the solvent towardthe treatment chamber, a mixing system for forming a mixed gascontaining a solvent vapor from the carrier gas feeding system and thesolvent dispensing system, and a control mechanism for controlling asolvent concentration of the mixed gas, wherein the control mechanismcontrols the solvent concentration to a first average concentrationduring a predetermined time after the substrate is carried into thetreatment chamber and the control mechanism controls the solventconcentration to a second average concentration higher than the firstaverage concentration after the predetermined time has passed; and asolvent replacement unit for replacing the solvent in the film.
 5. Theapparatus of forming a film as set forth in claim 4, wherein the controlmechanism increases the solvent concentration continuously correspondingto an increase of a temperature of the substrate after the substrate iscarried into the treatment chamber until the solvent concentrationreaches the second average concentration.
 6. The apparatus of forming afilm as set forth in claim 4, wherein the control mechanism controls atime-averaged solvent concentration so as to increase the solventconcentration continuously corresponding to an increase of a temperatureof the substrate after the substrate is carried into the treatmentchamber until the solvent concentration reaches the second averageconcentration.
 7. An aging unit, comprising: a treatment chamber havinga sealing mechanism, for accommodating a substrate having formed thereona film containing a solvent and particles or colloids of a startingsubstance of a film component; a heater for heating the substrate; acarrier gas feeding system for feeding the carrier gas toward thetreatment chamber; a solvent dispensing system for dispensing thesolvent toward the treatment chamber; a mixing system for forming amixed gas containing a solvent vapor from the carrier gas feeding systemand the solvent dispensing system; and a control mechanism forcontrolling a solvent concentration of the mixed gas, wherein thecontrol mechanism controls the solvent concentration to a first averageconcentration after the substrate is carried into the treatment chamberuntil a temperature of the substrate reaches a predetermined temperatureand the control mechanism controls the solvent concentration to a secondaverage concentration higher than the first average concentration afterreaching the predetermined temperature.
 8. The aging unit as set forthin claim 7, wherein the control mechanism increases the solventconcentration continuously corresponding to an increase of thetemperature of the substrate after the substrate is carried into thetreatment chamber until the solvent concentration reaches the secondaverage concentration.
 9. The aging unit as set forth in claim 7,wherein the control mechanism controls a time-averaged solventconcentration so as to increase the solvent concentration continuouslycorresponding to an increase of the temperature of the substrate afterthe substrate is carried into the treatment chamber until the solventconcentration reaches the second average concentration.
 10. An apparatusfor forming a film, comprising: a coating unit for coating, on a surfaceof a substrate, a coating liquid in which particles or colloids of astarting substance of a film component are dispersed in a solvent; anaging unit comprising a treatment chamber having a sealing mechanism,for accommodating the substrate having formed thereon the film, a heaterfor heating the substrate, a carrier gas feeding system for feeding thecarrier gas toward the treatment chamber, a solvent dispensing systemfor dispensing the solvent toward the treatment chamber, a mixing systemfor forming a mixed gas containing a solvent vapor from the carrier gasfeeding system and the solvent dispensing system, and a controlmechanism for controlling a solvent concentration of the mixed gas,wherein the control mechanism controls the solvent concentration to afirst average concentration after the substrate is carried into thetreatment chamber until a temperature of the substrate reaches apredetermined temperature and the control mechanism controls the solventconcentration to a second average concentration higher than the firstaverage concentration after reaching the predetermined temperature; anda solvent replacement unit for replacing the solvent in the film. 11.The apparatus of forming a film as set forth in claim 10, wherein thecontrol mechanism increases the solvent concentration continuouslycorresponding to an increase of the temperature of the substrate afterthe substrate is carried into the treatment chamber until the solventconcentration reaches the second average concentration.
 12. Theapparatus of forming a film as set forth in claim 10, wherein thecontrol mechanism controls a time-averaged solvent concentration so asto increase the solvent concentration continuously corresponding to anincrease of the temperature of the substrate after the substrate iscarried into the treatment chamber until the solvent concentrationreaches the second average concentration.